@staticmethod
def _wrap_unpack(bytestream, unpacker):
    """Return the first value when `unpacker` is run on `bytestream`.

        Parameters
        ----------
        bytestream : bytes
            The encoded data to unpack.
        unpacker : callable
            A callable function to use to unpack the data in `bytestream`. The
            `unpacker` should return a tuple containing unpacked values.
            Example: struct.Struct('>I').unpack.
        """
    return unpacker(bytestream)[0]
