def _get_protobuf_kind(kind):
if kind == Kind.CLIENT:<EOL><INDENT>return zipkin_pb2.Span.CLIENT<EOL><DEDENT>elif kind == Kind.SERVER:<EOL><INDENT>return zipkin_pb2.Span.SERVER<EOL><DEDENT>elif kind == Kind.PRODUCER:<EOL><INDENT>return zipkin_pb2.Span.PRODUCER<EOL><DEDENT>elif kind == Kind.CONSUMER:<EOL><INDENT>return zipkin_pb2.Span.CONSUMER<EOL><DEDENT>return None<EOL>
Converts py_zipkin's Kind to Protobuf's Kind.

    :param kind: py_zipkin's Kind.
    :type kind: py_zipkin.Kind
    :return: correcponding protobuf's kind value.
    :rtype: zipkin_pb2.Span.Kind