Add annotations to avatar.py, db.py, logging_util.py, unminify.py.

Also, fixed a a small type annotation in users.py because email must
be a string because emails don't support UTF-8 at this time (according
a comment in gravatar_hash in avatar.py).

zerver/lib/db.py

@@ -3,9 +3,16 @@ from __future__ import absolute_import
 import time
 from psycopg2.extensions import cursor, connection
 
+from typing import Callable, Optional, Iterable, Any, Dict, Union, TypeVar, \
+    Mapping, Sequence
+from six import text_type
+
+CursorObj = TypeVar('CursorObj', bound=cursor)
+
 # Similar to the tracking done in Django's CursorDebugWrapper, but done at the
 # psycopg2 cursor level so it works with SQLAlchemy.
 def wrapper_execute(self, action, sql, params=()):
+    # type: (CursorObj, Callable[[text_type, Optional[Union[Iterable[Any], Dict[text_type, Any]]]], CursorObj], text_type, Union[Iterable[Any], Dict[text_type, Any]]) -> CursorObj
     start = time.time()
     try:
         return action(sql, params)
@@ -20,25 +27,30 @@ class TimeTrackingCursor(cursor):
     """A psycopg2 cursor class that tracks the time spent executing queries."""
 
     def execute(self, query, vars=None):
+        # type: (text_type, Optional[Union[Iterable[Any], Dict[text_type, Any]]]) -> TimeTrackingCursor
         return wrapper_execute(self, super(TimeTrackingCursor, self).execute, query, vars)
 
     def executemany(self, query, vars):
+        # type: (text_type, Iterable[Any]) -> TimeTrackingCursor
         return wrapper_execute(self, super(TimeTrackingCursor, self).executemany, query, vars)
 
 class TimeTrackingConnection(connection):
     """A psycopg2 connection class that uses TimeTrackingCursors."""
 
     def __init__(self, *args, **kwargs):
+        # type: (Sequence[Any], Mapping[text_type, Any]) -> None
         self.queries = [] # type: List[Dict[str, str]]
         super(TimeTrackingConnection, self).__init__(*args, **kwargs)
 
     def cursor(self, name=None):
+        # type: (Optional[text_type]) -> TimeTrackingCursor
         if name is None:
             return super(TimeTrackingConnection, self).cursor(cursor_factory=TimeTrackingCursor)
         else:
             return super(TimeTrackingConnection, self).cursor(name, cursor_factory=TimeTrackingCursor)
 
 def reset_queries():
+    # type: () -> None
     from django.db import connections
     for conn in connections.all():
         if conn.connection is not None: