Add typing hints to github_tools with mypy enforcement (#771)

github_tools/github_helpers.py

@@ -9,11 +9,14 @@ Exceptions. See /LICENSE for license information.
 SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 """
 
+import argparse
 import os
+from typing import Dict, Generator, Optional, Tuple
 
 # https://pypi.org/project/gql/
-import gql
-import gql.transport.requests
+# gql is missing type annotations, so disable checking on around it.
+import gql  # type: ignore
+import gql.transport.requests  # type: ignore
 
 _ENV_TOKEN = "GITHUB_ACCESS_TOKEN"
 
@@ -25,7 +28,9 @@ PAGINATION = """pageInfo {
 totalCount"""
 
 
-def add_access_token_arg(parser, permissions):
+def add_access_token_arg(
+    parser: argparse.ArgumentParser, permissions: str
+) -> None:
     """Adds a flag to set the access token."""
     access_token = os.environ.get(_ENV_TOKEN, default=None)
     parser.add_argument(
@@ -42,7 +47,7 @@ def add_access_token_arg(parser, permissions):
 class Client(object):
     """A GitHub GraphQL client."""
 
-    def __init__(self, parsed_args):
+    def __init__(self, parsed_args: argparse.Namespace):
         """Connects to GitHub."""
         transport = gql.transport.requests.RequestsHTTPTransport(
             url="https://api.github.com/graphql",
@@ -50,11 +55,16 @@ class Client(object):
         )
         self._client = gql.Client(transport=transport)
 
-    def execute(self, query):
+    def execute(self, query: str) -> Dict:
         """Runs a query."""
-        return self._client.execute(gql.gql(query))
+        return self._client.execute(gql.gql(query))  # type: ignore
 
-    def execute_and_paginate(self, query, path, first_page=None):
+    def execute_and_paginate(
+        self,
+        query: str,
+        path: Tuple[str, ...],
+        first_page: Optional[Dict] = None,
+    ) -> Generator[Dict, None, None]:
         """Runs a query with pagination.
 
         Arguments: