Added types for typing

Author: Corvin Lasogga

instrumentation/opentelemetry-instrumentation-grpc/src/opentelemetry/instrumentation/grpc/_types.py

@@ -0,0 +1,29 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Internal types."""
+
+from typing import Dict, Iterator, TypeVar, Union
+
+import grpc
+
+
+Metadata = Dict[str, Union[str, bytes]]
+"""Metadata type."""
+
+ProtoMessage = TypeVar("ProtoMessage")
+"""Protobuf message type."""
+
+ProtoMessageOrIterator = Union[ProtoMessage, Iterator[ProtoMessage]]
+"""Type for a protobuf message or a iterator of protobuf messages."""