Applied Black plus some extra type hints

setup.py

@@ -33,7 +33,13 @@ setup(
     extras_require={
         "test": ["pytest", "black", "hypothesis"],
         "docs": ["sphinx_rtd_theme", "sphinx-autobuild", "codespell"],
-        "mypy": ["mypy", "types-click", "types-tabulate", "types-python-dateutil", "data-science-types"],
+        "mypy": [
+            "mypy",
+            "types-click",
+            "types-tabulate",
+            "types-python-dateutil",
+            "data-science-types",
+        ],
         "flake8": ["flake8"],
     },
     entry_points="""

sqlite_utils/db.py

@@ -277,7 +277,7 @@ class Database:
 
     def __init__(
         self,
-        filename_or_conn=None,
+        filename_or_conn: Union[str, pathlib.Path, sqlite3.Connection] = None,
         memory: bool = False,
         recreate: bool = False,
         recursive_triggers: bool = True,
@@ -331,7 +331,7 @@ class Database:
         """
         return self.table(table_name)
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "<Database {}>".format(self.conn)
 
     def register_function(
@@ -1069,7 +1069,7 @@ class Table(Queryable):
                 return next(iter(counts.values()))
         return self.count_where()
 
-    def exists(self):
+    def exists(self) -> bool:
         return self.name in self.db.table_names()
 
     @property