Merge pull request #492 from oasis-open/drop-six

Drop 'six' dependency (backwards breaking)

.isort.cfg

@@ -10,7 +10,6 @@ known_third_party =
     pytz,
     requests,
     simplejson,
-    six,
     sphinx,
     stix2patterns,
     taxii2client,

.pre-commit-config.yaml

@@ -23,3 +23,4 @@ repos:
         args: ["-c", "--diff"]
     -   id: isort
         name: Sort python imports (fixes files)
+exclude: ^stix2/canonicalization/

README.rst

@@ -21,6 +21,8 @@ Install with `pip <https://pip.pypa.io/en/stable/>`__:
 
   $ pip install stix2
 
+Note: The library requires Python 3.6+.
+
 Usage
 -----
 

docs/conf.py

@@ -4,7 +4,6 @@ import os
 import re
 import sys
 
-from six import class_types
 from sphinx.ext.autodoc import ClassDocumenter
 
 from stix2.base import _STIXBase
@@ -107,7 +106,7 @@ class STIXPropertyDocumenter(ClassDocumenter):
 
     @classmethod
     def can_document_member(cls, member, membername, isattr, parent):
-        return isinstance(member, class_types) and \
+        return isinstance(member, type) and \
                issubclass(member, _STIXBase) and \
                hasattr(member, '_properties')
 

setup.py

@@ -47,11 +47,11 @@ setup(
     ],
     keywords='stix stix2 json cti cyber threat intelligence',
     packages=find_packages(exclude=['*.test', '*.test.*']),
+    python_requires='>=3.6',
     install_requires=[
         'pytz',
         'requests',
         'simplejson',
-        'six>=1.13.0',
         'stix2-patterns>=1.2.0',
     ],
     project_urls={

stix2/base.py

@@ -5,7 +5,6 @@ import re
 import uuid
 
 import simplejson as json
-import six
 
 import stix2
 from stix2.canonicalization.Canonicalize import canonicalize
@@ -70,12 +69,9 @@ class _STIXBase(Mapping):
                 # InvalidValueError... so let those propagate.
                 raise
             except Exception as exc:
-                six.raise_from(
+                raise InvalidValueError(
-                    InvalidValueError(
+                    self.__class__, prop_name, reason=str(exc),
-                        self.__class__, prop_name, reason=str(exc),
+                ) from exc
-                    ),
-                    exc,
-                )
 
     # interproperty constraint methods
 
@@ -369,19 +365,8 @@ class _Observable(_STIXBase):
         if json_serializable_object:
 
             data = canonicalize(json_serializable_object, utf8=False)
-
+            uuid_ = uuid.uuid5(SCO_DET_ID_NAMESPACE, data)
-            # The situation is complicated w.r.t. python 2/3 behavior, so
+            id_ = "{}--{}".format(self._type, str(uuid_))
-            # I'd rather not rely on particular exceptions being raised to
-            # determine what to do.  Better to just check the python version
-            # directly.
-            if six.PY3:
-                uuid_ = uuid.uuid5(SCO_DET_ID_NAMESPACE, data)
-            else:
-                uuid_ = uuid.uuid5(
-                    SCO_DET_ID_NAMESPACE, data.encode("utf-8"),
-                )
-
-            id_ = "{}--{}".format(self._type, six.text_type(uuid_))
 
         return id_
 
@@ -447,7 +432,7 @@ def _make_json_serializable(value):
             for v in value
         ]
 
-    elif not isinstance(value, (int, float, six.string_types, bool)):
+    elif not isinstance(value, (int, float, str, bool)):
         # If a "simple" value which is not already JSON-serializable,
         # JSON-serialize to a string and use that as our JSON-serializable
         # value.  This applies to our datetime objects currently (timestamp

stix2/canonicalization/Canonicalize.py

@@ -20,12 +20,8 @@
 # JCS compatible JSON serializer for Python 3.x #
 #################################################
 
-# This file has been modified to be compatible with Python 2.x as well
-
 import re
 
-import six
-
 from stix2.canonicalization.NumberToJson import convert2Es6Format
 
 try:
@@ -55,10 +51,10 @@ ESCAPE_DCT = {
 }
 for i in range(0x20):
     ESCAPE_DCT.setdefault(chr(i), '\\u{0:04x}'.format(i))
+    #ESCAPE_DCT.setdefault(chr(i), '\\u%04x' % (i,))
 
 INFINITY = float('inf')
 
-
 def py_encode_basestring(s):
     """Return a JSON representation of a Python string
 
@@ -70,7 +66,6 @@ def py_encode_basestring(s):
 
 encode_basestring = (c_encode_basestring or py_encode_basestring)
 
-
 def py_encode_basestring_ascii(s):
     """Return an ASCII-only JSON representation of a Python string
 
@@ -83,6 +78,7 @@ def py_encode_basestring_ascii(s):
             n = ord(s)
             if n < 0x10000:
                 return '\\u{0:04x}'.format(n)
+                #return '\\u%04x' % (n,)
             else:
                 # surrogate pair
                 n -= 0x10000
@@ -96,7 +92,6 @@ encode_basestring_ascii = (
     c_encode_basestring_ascii or py_encode_basestring_ascii
 )
 
-
 class JSONEncoder(object):
     """Extensible JSON <http://json.org> encoder for Python data structures.
 
@@ -128,11 +123,10 @@ class JSONEncoder(object):
     """
     item_separator = ', '
     key_separator = ': '
-
     def __init__(
-        self, skipkeys=False, ensure_ascii=False,
+        self, *, skipkeys=False, ensure_ascii=False,
         check_circular=True, allow_nan=True, sort_keys=True,
-        indent=None, separators=(',', ':'), default=None,
+        indent=None, separators=(',', ':'), default=None
     ):
         """Constructor for JSONEncoder, with sensible defaults.
 
@@ -277,6 +271,7 @@ class JSONEncoder(object):
 
             return text
 
+
         if (
             _one_shot and c_make_encoder is not None
             and self.indent is None
@@ -294,11 +289,10 @@ class JSONEncoder(object):
             )
         return _iterencode(o, 0)
 
-
 def _make_iterencode(
     markers, _default, _encoder, _indent, _floatstr,
         _key_separator, _item_separator, _sort_keys, _skipkeys, _one_shot,
-        # HACK: hand-optimized bytecode; turn globals into locals
+        ## HACK: hand-optimized bytecode; turn globals into locals
         ValueError=ValueError,
         dict=dict,
         float=float,
@@ -362,10 +356,7 @@ def _make_iterencode(
                     chunks = _iterencode_dict(value, _current_indent_level)
                 else:
                     chunks = _iterencode(value, _current_indent_level)
-                # Below line commented-out for python2 compatibility
+                yield from chunks
-                # yield from chunks
-                for chunk in chunks:
-                    yield chunk
         if newline_indent is not None:
             _current_indent_level -= 1
             yield '\n' + _indent * _current_indent_level
@@ -397,8 +388,7 @@ def _make_iterencode(
         else:
             items = dct.items()
         for key, value in items:
-            # Replaced isinstance(key, str) with below to enable simultaneous python 2 & 3 compatibility
+            if isinstance(key, str):
-            if isinstance(key, six.string_types) or isinstance(key, six.binary_type):
                 pass
             # JavaScript is weakly typed for these, so it makes sense to
             # also allow them.  Many encoders seem to do something like this.
@@ -445,10 +435,7 @@ def _make_iterencode(
                     chunks = _iterencode_dict(value, _current_indent_level)
                 else:
                     chunks = _iterencode(value, _current_indent_level)
-                # Below line commented-out for python2 compatibility
+                yield from chunks
-                # yield from chunks
-                for chunk in chunks:
-                    yield chunk
         if newline_indent is not None:
             _current_indent_level -= 1
             yield '\n' + _indent * _current_indent_level
@@ -457,8 +444,7 @@ def _make_iterencode(
             del markers[markerid]
 
     def _iterencode(o, _current_indent_level):
-        # Replaced isinstance(o, str) with below to enable simultaneous python 2 & 3 compatibility
+        if isinstance(o, str):
-        if isinstance(o, six.string_types) or isinstance(o, six.binary_type):
             yield _encoder(o)
         elif o is None:
             yield 'null'
@@ -473,15 +459,9 @@ def _make_iterencode(
             # see comment for int/float in _make_iterencode
             yield convert2Es6Format(o)
         elif isinstance(o, (list, tuple)):
-            # Below line commented-out for python2 compatibility
+            yield from _iterencode_list(o, _current_indent_level)
-            # yield from _iterencode_list(o, _current_indent_level)
-            for thing in _iterencode_list(o, _current_indent_level):
-                yield thing
         elif isinstance(o, dict):
-            # Below line commented-out for python2 compatibility
+            yield from _iterencode_dict(o, _current_indent_level)
-            # yield from _iterencode_dict(o, _current_indent_level)
-            for thing in _iterencode_dict(o, _current_indent_level):
-                yield thing
         else:
             if markers is not None:
                 markerid = id(o)
@@ -489,23 +469,18 @@ def _make_iterencode(
                     raise ValueError("Circular reference detected")
                 markers[markerid] = o
             o = _default(o)
-            # Below line commented-out for python2 compatibility
+            yield from _iterencode(o, _current_indent_level)
-            # yield from _iterencode(o, _current_indent_level)
-            for thing in _iterencode(o, _current_indent_level):
-                yield thing
             if markers is not None:
                 del markers[markerid]
     return _iterencode
 
-
+def canonicalize(obj,utf8=True):
-def canonicalize(obj, utf8=True):
     textVal = JSONEncoder(sort_keys=True).encode(obj)
     if utf8:
         return textVal.encode()
     return textVal
 
-
+def serialize(obj,utf8=True):
-def serialize(obj, utf8=True):
     textVal = JSONEncoder(sort_keys=False).encode(obj)
     if utf8:
         return textVal.encode()

stix2/canonicalization/NumberToJson.py

@@ -21,40 +21,50 @@
 # Convert a Python double/float into an ES6/V8 compatible string #
 ##################################################################
 def convert2Es6Format(value):
-    # Convert double/float to str using the native Python formatter
+# Convert double/float to str using the native Python formatter
     fvalue = float(value)
-
+#
-    # Zero is a special case.  The following line takes "-0" case as well
+# Zero is a special case.  The following line takes "-0" case as well
+#
     if fvalue == 0:
         return '0'
-
+#
-    # The rest of the algorithm works on the textual representation only
+# The rest of the algorithm works on the textual representation only
+#
     pyDouble = str(fvalue)
-
+#
-    # The following line catches the "inf" and "nan" values returned by str(fvalue)
+# The following line catches the "inf" and "nan" values returned by str(fvalue)
+#
     if pyDouble.find('n') >= 0:
         raise ValueError("Invalid JSON number: " + pyDouble)
-
+#
-    # Save sign separately, it doesn't have any role in the algorithm
+# Save sign separately, it doesn't have any role in the algorithm
+#
     pySign = ''
     if pyDouble.find('-') == 0:
         pySign = '-'
         pyDouble = pyDouble[1:]
-
+#
-    # Now we should only have valid non-zero values
+# Now we should only have valid non-zero values
+#
     pyExpStr = ''
     pyExpVal = 0
     q = pyDouble.find('e')
     if q > 0:
-        # Grab the exponent and remove it from the number
+#
+# Grab the exponent and remove it from the number
+#
         pyExpStr = pyDouble[q:]
         if pyExpStr[2:3] == '0':
-            # Supress leading zero on exponents
+#
+# Supress leading zero on exponents
+#
             pyExpStr = pyExpStr[:2] + pyExpStr[3:]
         pyDouble = pyDouble[0:q]
         pyExpVal = int(pyExpStr[1:])
-
+#
-    # Split number in pyFirst + pyDot + pyLast
+# Split number in pyFirst + pyDot + pyLast
+#
     pyFirst = pyDouble
     pyDot = ''
     pyLast = ''
@@ -63,33 +73,40 @@ def convert2Es6Format(value):
         pyDot = '.'
         pyFirst = pyDouble[:q]
         pyLast = pyDouble[q + 1:]
-
+#
-    # Now the string is split into: pySign + pyFirst + pyDot + pyLast + pyExpStr
+# Now the string is split into: pySign + pyFirst + pyDot + pyLast + pyExpStr
+#
     if pyLast == '0':
-        # Always remove trailing .0
+#
+# Always remove trailing .0
+#
         pyDot = ''
         pyLast = ''
-
     if pyExpVal > 0 and pyExpVal < 21:
-        # Integers are shown as is with up to 21 digits
+#
+# Integers are shown as is with up to 21 digits
+#
         pyFirst += pyLast
         pyLast = ''
         pyDot = ''
         pyExpStr = ''
         q = pyExpVal - len(pyFirst)
         while q >= 0:
-            q -= 1
+            q -= 1;
             pyFirst += '0'
     elif pyExpVal < 0 and pyExpVal > -7:
-        # Small numbers are shown as 0.etc with e-6 as lower limit
+#
+# Small numbers are shown as 0.etc with e-6 as lower limit
+#
         pyLast = pyFirst + pyLast
         pyFirst = '0'
         pyDot = '.'
         pyExpStr = ''
         q = pyExpVal
         while q < -1:
-            q += 1
+            q += 1;
             pyLast = '0' + pyLast
-
+#
-    # The resulting sub-strings are concatenated
+# The resulting sub-strings are concatenated
+#
     return pySign + pyFirst + pyDot + pyLast + pyExpStr

stix2/custom.py

@@ -1,7 +1,5 @@
 from collections import OrderedDict
 
-import six
-
 from .base import _cls_init
 from .registration import (
     _register_marking, _register_object, _register_observable,
@@ -13,14 +11,11 @@ def _get_properties_dict(properties):
     try:
         return OrderedDict(properties)
     except TypeError as e:
-        six.raise_from(
+        raise ValueError(
-            ValueError(
+            "properties must be dict-like, e.g. a list "
-                "properties must be dict-like, e.g. a list "
+            "containing tuples.  For example, "
-                "containing tuples.  For example, "
+            "[('property1', IntegerProperty())]",
-                "[('property1', IntegerProperty())]",
+        ) from e
-            ),
-            e,
-        )
 
 
 def _custom_object_builder(cls, type, properties, version, base_class):

stix2/datastore/__init__.py

@@ -15,8 +15,6 @@ Python STIX2 DataStore API.
 from abc import ABCMeta, abstractmethod
 import uuid
 
-from six import with_metaclass
-
 from stix2.datastore.filters import Filter, FilterSet
 from stix2.utils import deduplicate
 
@@ -219,7 +217,7 @@ class DataStoreMixin(object):
             raise AttributeError(msg % self.__class__.__name__)
 
 
-class DataSink(with_metaclass(ABCMeta)):
+class DataSink(metaclass=ABCMeta):
     """An implementer will create a concrete subclass from
     this class for the specific DataSink.
 
@@ -245,7 +243,7 @@ class DataSink(with_metaclass(ABCMeta)):
         """
 
 
-class DataSource(with_metaclass(ABCMeta)):
+class DataSource(metaclass=ABCMeta):
     """An implementer will create a concrete subclass from
     this class for the specific DataSource.
 

stix2/datastore/filesystem.py

@@ -6,8 +6,6 @@ import os
 import re
 import stat
 
-import six
-
 from stix2 import v20, v21
 from stix2.base import _STIXBase
 from stix2.datastore import (
@@ -116,7 +114,7 @@ def _update_allow(allow_set, value):
 
     """
     adding_seq = hasattr(value, "__iter__") and \
-        not isinstance(value, six.string_types)
+        not isinstance(value, str)
 
     if allow_set is None:
         allow_set = set()

stix2/datastore/filters.py

@@ -3,8 +3,6 @@
 import collections
 from datetime import datetime
 
-import six
-
 import stix2.utils
 
 """Supported filter operations"""
@@ -12,8 +10,7 @@ FILTER_OPS = ['=', '!=', 'in', '>', '<', '>=', '<=', 'contains']
 
 """Supported filter value types"""
 FILTER_VALUE_TYPES = (
-    bool, dict, float, int, list, tuple, six.string_types,
+    bool, dict, float, int, list, tuple, str, datetime,
-    datetime,
 )
 
 
@@ -84,7 +81,7 @@ class Filter(collections.namedtuple('Filter', ['property', 'op', 'value'])):
         # If filtering on a timestamp property and the filter value is a string,
         # try to convert the filter value to a datetime instance.
         if isinstance(stix_obj_property, datetime) and \
-                isinstance(self.value, six.string_types):
+                isinstance(self.value, str):
             filter_value = stix2.utils.parse_into_datetime(self.value)
         else:
             filter_value = self.value

stix2/markings/utils.py

@@ -2,8 +2,6 @@
 
 import collections
 
-import six
-
 from stix2 import exceptions, utils
 
 
@@ -129,7 +127,7 @@ def compress_markings(granular_markings):
             {'marking_ref': item, 'selectors': sorted(selectors)}
             if utils.is_marking(item) else
             {'lang': item, 'selectors': sorted(selectors)}
-            for item, selectors in six.iteritems(map_)
+            for item, selectors in map_.items()
         ]
 
     return compressed
@@ -230,7 +228,7 @@ def iterpath(obj, path=None):
     if path is None:
         path = []
 
-    for varname, varobj in iter(sorted(six.iteritems(obj))):
+    for varname, varobj in iter(sorted(obj.items())):
         path.append(varname)
         yield (path, varobj)
 

stix2/pattern_visitor.py

@@ -3,7 +3,6 @@
 import importlib
 import inspect
 
-from six import text_type
 from stix2patterns.exceptions import ParseException
 from stix2patterns.grammars.STIXPatternParser import TerminalNode
 from stix2patterns.v20.grammars.STIXPatternParser import \
@@ -263,7 +262,7 @@ class STIXPatternVisitorForSTIX2():
                 property_path.append(
                     self.instantiate(
                         "ListObjectPathComponent",
-                        current.property_name if isinstance(current, BasicObjectPathComponent) else text_type(current),
+                        current.property_name if isinstance(current, BasicObjectPathComponent) else str(current),
                         next.value,
                     ),
                 )
@@ -286,7 +285,7 @@ class STIXPatternVisitorForSTIX2():
         if isinstance(first_component, TerminalNode):
             step = first_component.getText()
         else:
-            step = text_type(first_component)
+            step = str(first_component)
         # if step.endswith("_ref"):
         #     return stix2.ReferenceObjectPathComponent(step)
         # else:

stix2/patterns.py

@@ -5,8 +5,6 @@ import binascii
 import datetime
 import re
 
-import six
-
 from .utils import parse_into_datetime
 
 
@@ -15,7 +13,7 @@ def escape_quotes_and_backslashes(s):
 
 
 def quote_if_needed(x):
-    if isinstance(x, six.string_types):
+    if isinstance(x, str):
         if x.find("-") != -1:
             if not x.startswith("'"):
                 return "'" + x + "'"

stix2/properties.py

@@ -7,8 +7,6 @@ import inspect
 import re
 import uuid
 
-from six import string_types, text_type
-
 from .base import _STIXBase
 from .exceptions import (
     CustomContentError, DictionaryKeyError, MissingPropertiesError,
@@ -227,7 +225,7 @@ class ListProperty(Property):
         except TypeError:
             raise ValueError("must be an iterable.")
 
-        if isinstance(value, (_STIXBase, string_types)):
+        if isinstance(value, (_STIXBase, str)):
             value = [value]
 
         if isinstance(self.contained, Property):
@@ -268,8 +266,8 @@ class StringProperty(Property):
         super(StringProperty, self).__init__(**kwargs)
 
     def clean(self, value):
-        if not isinstance(value, string_types):
+        if not isinstance(value, str):
-            return text_type(value)
+            return str(value)
         return value
 
 

stix2/test/v20/test_datastore_filters.py

@@ -128,18 +128,17 @@ def test_filter_value_type_check():
 
     with pytest.raises(TypeError) as excinfo:
         Filter('created', '=', object())
-    # On Python 2, the type of object() is `<type 'object'>` On Python 3, it's `<class 'object'>`.
+    assert "'<class 'object'>'" in str(excinfo.value)
-    assert any([s in str(excinfo.value) for s in ["<type 'object'>", "'<class 'object'>'"]])
     assert "is not supported. The type must be a Python immutable type or dictionary" in str(excinfo.value)
 
     with pytest.raises(TypeError) as excinfo:
         Filter("type", "=", complex(2, -1))
-    assert any([s in str(excinfo.value) for s in ["<type 'complex'>", "'<class 'complex'>'"]])
+    assert "'<class 'complex'>'" in str(excinfo.value)
     assert "is not supported. The type must be a Python immutable type or dictionary" in str(excinfo.value)
 
     with pytest.raises(TypeError) as excinfo:
         Filter("type", "=", set([16, 23]))
-    assert any([s in str(excinfo.value) for s in ["<type 'set'>", "'<class 'set'>'"]])
+    assert "'<class 'set'>'" in str(excinfo.value)
     assert "is not supported. The type must be a Python immutable type or dictionary" in str(excinfo.value)
 
 

stix2/test/v20/test_datastore_taxii.py

@@ -3,7 +3,6 @@ import json
 from medallion.filters.basic_filter import BasicFilter
 import pytest
 from requests.models import Response
-import six
 from taxii2client.common import _filter_kwargs_to_query_params
 from taxii2client.v20 import Collection
 
@@ -27,7 +26,7 @@ class MockTAXIICollectionEndpoint(Collection):
 
     def add_objects(self, bundle):
         self._verify_can_write()
-        if isinstance(bundle, six.string_types):
+        if isinstance(bundle, str):
             bundle = json.loads(bundle)
         for object in bundle.get("objects", []):
             self.objects.append(object)

stix2/test/v21/test_datastore_filters.py

@@ -146,18 +146,17 @@ def test_filter_value_type_check():
 
     with pytest.raises(TypeError) as excinfo:
         Filter('created', '=', object())
-    # On Python 2, the type of object() is `<type 'object'>` On Python 3, it's `<class 'object'>`.
+    assert "'<class 'object'>'" in str(excinfo.value)
-    assert any([s in str(excinfo.value) for s in ["<type 'object'>", "'<class 'object'>'"]])
     assert "is not supported. The type must be a Python immutable type or dictionary" in str(excinfo.value)
 
     with pytest.raises(TypeError) as excinfo:
         Filter("type", "=", complex(2, -1))
-    assert any([s in str(excinfo.value) for s in ["<type 'complex'>", "'<class 'complex'>'"]])
+    assert "'<class 'complex'>'" in str(excinfo.value)
     assert "is not supported. The type must be a Python immutable type or dictionary" in str(excinfo.value)
 
     with pytest.raises(TypeError) as excinfo:
         Filter("type", "=", set([16, 23]))
-    assert any([s in str(excinfo.value) for s in ["<type 'set'>", "'<class 'set'>'"]])
+    assert "'<class 'set'>'" in str(excinfo.value)
     assert "is not supported. The type must be a Python immutable type or dictionary" in str(excinfo.value)
 
 

stix2/test/v21/test_datastore_taxii.py

@@ -3,7 +3,6 @@ import json
 from medallion.filters.basic_filter import BasicFilter
 import pytest
 from requests.models import Response
-import six
 from taxii2client.common import _filter_kwargs_to_query_params
 from taxii2client.v21 import Collection
 
@@ -27,7 +26,7 @@ class MockTAXIICollectionEndpoint(Collection):
 
     def add_objects(self, bundle):
         self._verify_can_write()
-        if isinstance(bundle, six.string_types):
+        if isinstance(bundle, str):
             bundle = json.loads(bundle)
         for object in bundle.get("objects", []):
             self.objects.append(object)

stix2/test/v21/test_deterministic_ids.py

@@ -3,7 +3,6 @@ import datetime
 import uuid
 
 import pytest
-import six
 
 import stix2.base
 import stix2.canonicalization.Canonicalize
@@ -31,12 +30,7 @@ def _make_uuid5(name):
     """
     Make a STIX 2.1+ compliant UUIDv5 from a "name".
     """
-    if six.PY3:
+    uuid_ = uuid.uuid5(SCO_DET_ID_NAMESPACE, name)
-        uuid_ = uuid.uuid5(SCO_DET_ID_NAMESPACE, name)
-    else:
-        uuid_ = uuid.uuid5(
-            SCO_DET_ID_NAMESPACE, name.encode("utf-8"),
-        )
 
     return uuid_
 

stix2/utils.py

@@ -7,7 +7,6 @@ import json
 import re
 
 import pytz
-import six
 
 import stix2.registry as mappings
 import stix2.version
@@ -70,7 +69,7 @@ def _to_enum(value, enum_type, enum_default=None):
     if not isinstance(value, enum_type):
         if value is None and enum_default is not None:
             value = enum_default
-        elif isinstance(value, six.string_types):
+        elif isinstance(value, str):
             value = enum_type[value.upper()]
         else:
             raise TypeError(

stix2/v20/common.py

@@ -3,8 +3,6 @@
 from collections import OrderedDict
 import copy
 
-import six
-
 from ..custom import _custom_marking_builder
 from ..markings import _MarkingsMixin
 from ..markings.utils import check_tlp_marking
@@ -21,7 +19,7 @@ def _should_set_millisecond(cr, marking_type):
     if marking_type == TLPMarking:
         return True
     # otherwise,  precision is kept from how it was given
-    if isinstance(cr, six.string_types):
+    if isinstance(cr, str):
         if '.' in cr:
             return True
         else:

stix2/v21/sdo.py

@@ -2,9 +2,9 @@
 
 from collections import OrderedDict
 import itertools
+from urllib.parse import quote_plus
 import warnings
 
-from six.moves.urllib.parse import quote_plus
 from stix2patterns.validator import run_validator
 
 from ..custom import _custom_object_builder