code: def get_unique_schema_id(schema):
      # type: (GraphQLSchema) -> str
      
      assert isinstance(schema, GraphQLSchema), (
          "Must receive a GraphQLSchema as schema. Received {}"
      ).format(repr(schema))
  
      if schema not in _cached_schemas:
          _cached_schemas[schema] = sha1(str(schema).encode("utf-8")).hexdigest()
      return _cached_schemas[schema]
docs: Get a unique id given a GraphQLSchema