Move iter_over_arguments to a separate file

jedi/inference/gradual/generics.py

@@ -0,0 +1,27 @@
+from jedi.inference.base_value import ValueSet, Value, \
+    iterator_to_value_set, LazyValueWrapper, ValueWrapper
+from jedi.inference.value.iterable import SequenceLiteralValue
+from jedi.inference.helpers import is_string
+
+
+def iter_over_arguments(maybe_tuple_value, defining_context):
+    def iterate():
+        if isinstance(maybe_tuple_value, SequenceLiteralValue):
+            for lazy_value in maybe_tuple_value.py__iter__(contextualized_node=None):
+                yield lazy_value.infer()
+        else:
+            yield ValueSet([maybe_tuple_value])
+
+    def resolve_forward_references(value_set):
+        for value in value_set:
+            if is_string(value):
+                from jedi.inference.gradual.annotation import _get_forward_reference_node
+                node = _get_forward_reference_node(defining_context, value.get_safe_value())
+                if node is not None:
+                    for c in defining_context.infer_node(node):
+                        yield c
+            else:
+                yield value
+
+    for value_set in iterate():
+        yield ValueSet(resolve_forward_references(value_set))