diff --git a/jedi/common/__init__.py b/jedi/common/__init__.py
index ba2e2f44..b190d863 100644
--- a/jedi/common/__init__.py
+++ b/jedi/common/__init__.py
@@ -1,2 +1 @@
-from jedi.common.context import ContextSet, NO_CONTEXTS, \
-    iterator_to_context_set
+from jedi.common.context import BaseContextSet
diff --git a/jedi/common/context.py b/jedi/common/context.py
index ecf12a5a..95839ea9 100644
--- a/jedi/common/context.py
+++ b/jedi/common/context.py
@@ -1,4 +1,4 @@
-class ContextSet(object):
+class BaseContextSet(object):
     def __init__(self, *args):
         self._set = set(args)
 
@@ -20,14 +20,14 @@ class ContextSet(object):
         aggregated = set()
         sets = list(sets)
         for set_ in sets:
-            if isinstance(set_, ContextSet):
+            if isinstance(set_, BaseContextSet):
                 aggregated |= set_._set
             else:
                 aggregated |= set_
         return cls.from_set(aggregated)
 
     def __or__(self, other):
-        return ContextSet.from_set(self._set | other._set)
+        return type(self).from_set(self._set | other._set)
 
     def __iter__(self):
         for element in self._set:
@@ -43,22 +43,12 @@ class ContextSet(object):
         return '%s(%s)' % (self.__class__.__name__, ', '.join(str(s) for s in self._set))
 
     def filter(self, filter_func):
-        return ContextSet.from_iterable(filter(filter_func, self._set))
+        return type(self).from_iterable(filter(filter_func, self._set))
 
     def __getattr__(self, name):
         def mapper(*args, **kwargs):
-            return ContextSet.from_sets(
+            return type(self).from_sets(
                 getattr(context, name)(*args, **kwargs)
                 for context in self._set
             )
         return mapper
-
-
-def iterator_to_context_set(func):
-    def wrapper(*args, **kwargs):
-        return ContextSet.from_iterable(func(*args, **kwargs))
-
-    return wrapper
-
-
-NO_CONTEXTS = ContextSet()
diff --git a/jedi/evaluate/__init__.py b/jedi/evaluate/__init__.py
index 96651196..7bd17c55 100644
--- a/jedi/evaluate/__init__.py
+++ b/jedi/evaluate/__init__.py
@@ -82,8 +82,8 @@ from jedi.evaluate import helpers
 from jedi.evaluate import pep0484
 from jedi.evaluate.filters import TreeNameDefinition, ParamName
 from jedi.evaluate.instance import AnonymousInstance, BoundMethod
-from jedi.evaluate.context import ContextualizedName, ContextualizedNode
-from jedi.common import ContextSet, NO_CONTEXTS
+from jedi.evaluate.context import ContextualizedName, ContextualizedNode, \
+    ContextSet, NO_CONTEXTS
 from jedi import parser_utils
 
 
diff --git a/jedi/evaluate/compiled/__init__.py b/jedi/evaluate/compiled/__init__.py
index c4d3ae32..ab9ea8f5 100644
--- a/jedi/evaluate/compiled/__init__.py
+++ b/jedi/evaluate/compiled/__init__.py
@@ -13,9 +13,8 @@ from jedi import debug
 from jedi.cache import underscore_memoization, memoize_method
 from jedi.evaluate.filters import AbstractFilter, AbstractNameDefinition, \
     ContextNameMixin
-from jedi.evaluate.context import Context, LazyKnownContext
+from jedi.evaluate.context import Context, LazyKnownContext, ContextSet
 from jedi.evaluate.compiled.getattr_static import getattr_static
-from jedi.common import ContextSet
 from . import fake
 
 
diff --git a/jedi/evaluate/compiled/mixed.py b/jedi/evaluate/compiled/mixed.py
index 2fac34ff..3b397a31 100644
--- a/jedi/evaluate/compiled/mixed.py
+++ b/jedi/evaluate/compiled/mixed.py
@@ -9,10 +9,9 @@ from jedi import settings
 from jedi.evaluate import compiled
 from jedi.cache import underscore_memoization
 from jedi.evaluate import imports
-from jedi.evaluate.context import Context
+from jedi.evaluate.context import Context, ContextSet
 from jedi.evaluate.cache import evaluator_function_cache
 from jedi.evaluate.compiled.getattr_static import getattr_static
-from jedi.common import ContextSet
 
 
 class MixedObject(object):
diff --git a/jedi/evaluate/context.py b/jedi/evaluate/context.py
index 7ff57d5d..6202e99f 100644
--- a/jedi/evaluate/context.py
+++ b/jedi/evaluate/context.py
@@ -1,7 +1,7 @@
 from jedi._compatibility import Python3Method
 from parso.python.tree import ExprStmt, CompFor
 from jedi.parser_utils import clean_scope_docstring, get_doc_with_call_signature
-from jedi.common import ContextSet, NO_CONTEXTS
+from jedi.common import BaseContextSet
 
 
 class Context(object):
@@ -204,3 +204,17 @@ class ContextualizedName(ContextualizedNode):
             compare = node
             node = node.parent
         return indexes
+
+
+class ContextSet(BaseContextSet):
+    pass
+
+
+NO_CONTEXTS = ContextSet()
+
+
+def iterator_to_context_set(func):
+    def wrapper(*args, **kwargs):
+        return ContextSet.from_iterable(func(*args, **kwargs))
+
+    return wrapper
diff --git a/jedi/evaluate/docstrings.py b/jedi/evaluate/docstrings.py
index ea471811..f80036bd 100644
--- a/jedi/evaluate/docstrings.py
+++ b/jedi/evaluate/docstrings.py
@@ -21,11 +21,11 @@ from textwrap import dedent
 from parso import parse
 
 from jedi._compatibility import u
-from jedi.evaluate.utils import unite, indent_block
-from jedi.evaluate import context
+from jedi.evaluate.utils import indent_block
 from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate.iterable import SequenceLiteralContext, FakeSequence
-from jedi.common import iterator_to_context_set, ContextSet, NO_CONTEXTS
+from jedi.evaluate.context import iterator_to_context_set, ContextSet, \
+    NO_CONTEXTS, LazyKnownContexts
 
 
 DOCSTRING_PARAM_PATTERNS = [
@@ -241,7 +241,7 @@ def _execute_array_values(evaluator, array):
                 _execute_array_values(evaluator, typ)
                 for typ in lazy_context.infer()
             )
-            values.append(context.LazyKnownContexts(objects))
+            values.append(LazyKnownContexts(objects))
         return set([FakeSequence(evaluator, array.array_type, values)])
     else:
         return array.execute_evaluated()
diff --git a/jedi/evaluate/dynamic.py b/jedi/evaluate/dynamic.py
index 9857f312..f5b4cd0d 100644
--- a/jedi/evaluate/dynamic.py
+++ b/jedi/evaluate/dynamic.py
@@ -25,7 +25,7 @@ from jedi.evaluate import imports
 from jedi.evaluate.param import TreeArguments, create_default_params
 from jedi.evaluate.helpers import is_stdlib_path
 from jedi.evaluate.utils import to_list
-from jedi.common import ContextSet
+from jedi.evaluate.context import ContextSet
 from jedi.parser_utils import get_parent_scope
 
 
diff --git a/jedi/evaluate/filters.py b/jedi/evaluate/filters.py
index e3edb1eb..f4c6463b 100644
--- a/jedi/evaluate/filters.py
+++ b/jedi/evaluate/filters.py
@@ -6,7 +6,7 @@ from abc import abstractmethod
 
 from parso.tree import search_ancestor
 from jedi.evaluate import flow_analysis
-from jedi.common import ContextSet
+from jedi.evaluate.context import ContextSet
 from jedi.parser_utils import get_parent_scope
 from jedi.evaluate.utils import to_list
 
diff --git a/jedi/evaluate/finder.py b/jedi/evaluate/finder.py
index 15d45108..fd37adac 100644
--- a/jedi/evaluate/finder.py
+++ b/jedi/evaluate/finder.py
@@ -18,7 +18,6 @@ check for -> a is a string). There's big potential in these checks.
 from parso.python import tree
 from parso.tree import search_ancestor
 from jedi import debug
-from jedi.evaluate.utils import unite
 from jedi import settings
 from jedi.evaluate import representation as er
 from jedi.evaluate.instance import AbstractInstanceContext
@@ -31,8 +30,7 @@ from jedi.evaluate import flow_analysis
 from jedi.evaluate import param
 from jedi.evaluate import helpers
 from jedi.evaluate.filters import get_global_filters, TreeNameDefinition
-from jedi.evaluate.context import ContextualizedName, ContextualizedNode
-from jedi.common import ContextSet
+from jedi.evaluate.context import ContextualizedName, ContextualizedNode, ContextSet
 from jedi.parser_utils import is_scope, get_parent_scope
 
 
diff --git a/jedi/evaluate/imports.py b/jedi/evaluate/imports.py
index 716fa35f..f06d3b66 100644
--- a/jedi/evaluate/imports.py
+++ b/jedi/evaluate/imports.py
@@ -31,7 +31,7 @@ from jedi.evaluate import analysis
 from jedi.evaluate.utils import unite
 from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate.filters import AbstractNameDefinition
-from jedi.common import ContextSet, NO_CONTEXTS
+from jedi.evaluate.context import ContextSet, NO_CONTEXTS
 
 
 # This memoization is needed, because otherwise we will infinitely loop on
diff --git a/jedi/evaluate/instance.py b/jedi/evaluate/instance.py
index f1116707..747f5802 100644
--- a/jedi/evaluate/instance.py
+++ b/jedi/evaluate/instance.py
@@ -4,13 +4,13 @@ from jedi._compatibility import is_py3
 from jedi import debug
 from jedi.evaluate import compiled
 from jedi.evaluate import filters
-from jedi.evaluate.context import Context, LazyKnownContext, LazyKnownContexts
+from jedi.evaluate.context import Context, LazyKnownContext, LazyKnownContexts, \
+    ContextSet, iterator_to_context_set, NO_CONTEXTS
 from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate.param import AbstractArguments, AnonymousArguments
 from jedi.cache import memoize_method
 from jedi.evaluate import representation as er
 from jedi.evaluate import iterable
-from jedi.common import ContextSet, iterator_to_context_set, NO_CONTEXTS
 from jedi.parser_utils import get_parent_scope
 
 
diff --git a/jedi/evaluate/iterable.py b/jedi/evaluate/iterable.py
index 2b8425ab..be62ecb0 100644
--- a/jedi/evaluate/iterable.py
+++ b/jedi/evaluate/iterable.py
@@ -22,20 +22,20 @@ It is important to note that:
 """
 from jedi import debug
 from jedi import settings
-from jedi.evaluate.utils import unite, safe_property
+from jedi.evaluate.utils import safe_property
 from jedi._compatibility import unicode, zip_longest, is_py3
 from jedi.evaluate.utils import to_list
 from jedi.evaluate import compiled
 from jedi.evaluate import helpers
 from jedi.evaluate import analysis
 from jedi.evaluate import pep0484
-from jedi.evaluate import context
 from jedi.evaluate import precedence
 from jedi.evaluate import recursion
 from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate.filters import DictFilter, AbstractNameDefinition, \
     ParserTreeFilter
-from jedi.common import ContextSet, NO_CONTEXTS
+from jedi.evaluate import context
+from jedi.evaluate.context import ContextSet, NO_CONTEXTS
 from jedi.parser_utils import get_comp_fors
 
 
diff --git a/jedi/evaluate/param.py b/jedi/evaluate/param.py
index a914d81a..f5a183a1 100644
--- a/jedi/evaluate/param.py
+++ b/jedi/evaluate/param.py
@@ -10,7 +10,7 @@ from jedi.evaluate import context
 from jedi.evaluate import docstrings
 from jedi.evaluate import pep0484
 from jedi.evaluate.filters import ParamName
-from jedi.common import NO_CONTEXTS
+from jedi.evaluate.context import NO_CONTEXTS
 
 
 def add_argument_issue(parent_context, error_name, lazy_context, message):
diff --git a/jedi/evaluate/pep0484.py b/jedi/evaluate/pep0484.py
index 0fa7ca41..869cf8a8 100644
--- a/jedi/evaluate/pep0484.py
+++ b/jedi/evaluate/pep0484.py
@@ -27,8 +27,7 @@ from parso.python import tree
 
 from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate import compiled
-from jedi.evaluate.context import LazyTreeContext
-from jedi.common import NO_CONTEXTS, ContextSet
+from jedi.evaluate.context import LazyTreeContext, NO_CONTEXTS, ContextSet
 from jedi import debug
 from jedi import _compatibility
 from jedi import parser_utils
diff --git a/jedi/evaluate/precedence.py b/jedi/evaluate/precedence.py
index 8206dac5..7e054c05 100644
--- a/jedi/evaluate/precedence.py
+++ b/jedi/evaluate/precedence.py
@@ -7,7 +7,7 @@ from jedi._compatibility import unicode
 from jedi import debug
 from jedi.evaluate.compiled import CompiledObject, create, builtin_from_name
 from jedi.evaluate import analysis
-from jedi.common import ContextSet, NO_CONTEXTS, iterator_to_context_set
+from jedi.evaluate.context import ContextSet, NO_CONTEXTS, iterator_to_context_set
 
 # Maps Python syntax to the operator module.
 COMPARISON_OPERATORS = {
diff --git a/jedi/evaluate/recursion.py b/jedi/evaluate/recursion.py
index ebc71f09..02f13db9 100644
--- a/jedi/evaluate/recursion.py
+++ b/jedi/evaluate/recursion.py
@@ -29,7 +29,7 @@ therefore the quality might not always be maximal.
 from contextlib import contextmanager
 
 from jedi import debug
-from jedi.common import NO_CONTEXTS
+from jedi.evaluate.context import NO_CONTEXTS
 
 
 recursion_limit = 15
diff --git a/jedi/evaluate/representation.py b/jedi/evaluate/representation.py
index c427b786..fb7e81d5 100644
--- a/jedi/evaluate/representation.py
+++ b/jedi/evaluate/representation.py
@@ -63,8 +63,8 @@ from jedi.evaluate.filters import ParserTreeFilter, FunctionExecutionFilter, \
     ParamName, AnonymousInstanceParamName, TreeNameDefinition, \
     ContextNameMixin
 from jedi.evaluate import context
-from jedi.evaluate.context import ContextualizedNode
-from jedi.common import NO_CONTEXTS, ContextSet, iterator_to_context_set
+from jedi.evaluate.context import ContextualizedNode, NO_CONTEXTS, \
+    ContextSet, iterator_to_context_set
 from jedi import parser_utils
 from jedi.evaluate.parser_cache import get_yield_exprs
 
diff --git a/jedi/evaluate/stdlib.py b/jedi/evaluate/stdlib.py
index 169e709e..0f85b62d 100644
--- a/jedi/evaluate/stdlib.py
+++ b/jedi/evaluate/stdlib.py
@@ -23,8 +23,8 @@ from jedi import debug
 from jedi.evaluate import precedence
 from jedi.evaluate import param
 from jedi.evaluate import analysis
-from jedi.evaluate.context import LazyTreeContext, ContextualizedNode
-from jedi.common import NO_CONTEXTS, ContextSet
+from jedi.evaluate.context import LazyTreeContext, ContextualizedNode, \
+    NO_CONTEXTS, ContextSet
 
 # Now this is all part of fake tuples in Jedi. However super doesn't work on
 # __init__ and __new__ doesn't work at all. So adding this to nametuples is