-type error() :: {error, atom()}.

-type option() :: {async, pid()}.

-type options() :: [option()].

-type response() ::
          #response{op_code :: non_neg_integer() | undefined,
                    key_length :: non_neg_integer() | undefined,
                    extras_length :: non_neg_integer() | undefined,
                    data_type :: non_neg_integer() | undefined,
                    status :: non_neg_integer() | undefined,
                    body_length :: non_neg_integer() | undefined,
                    opaque :: non_neg_integer() | undefined,
                    cas :: non_neg_integer() | undefined,
                    extras :: binary() | undefined,
                    key :: binary() | undefined,
                    value :: binary() | undefined}.