mypy

Author: bmartinn

src/pip/_internal/req/__init__.py

@@ -19,7 +19,7 @@
     Pool = None   # type: ignore
 
 if MYPY_CHECK_RUNNING:
-    from typing import Any, List, Sequence, Union
+    from typing import Any, List, Sequence, Optional
 
 __all__ = [
     "RequirementSet", "InstallRequirement",
@@ -60,7 +60,7 @@ def install_given_reqs(
         )
 
     # pre allocate installed package names
-    installed = [None] * len(to_install)
+    installed = [None] * len(to_install)  # type: ignore
     install_args = [install_options, global_options, args, kwargs]
 
     if Pool is not None:
@@ -94,7 +94,7 @@ def __single_install(
         a_requirement,     # type: InstallRequirement
         allow_raise=False  # type: bool
 ):
-    # type: (...) -> Union[InstallationResult, None]
+    # type: (...) -> Optional[InstallationResult]
     """
     Install a single requirement, returns InstallationResult