Concatenate multiple serialized binders into one byte string.

def merge_bytes(binder_strings):
    """Concatenate multiple serialized binders into one byte string."""
    output = None
    for byte_string in binder_strings:
        binder = Binder().from_bytes(byte_string)
        if output is None:
            output = binder
        else:
            output.merge(binder)
    return output.to_bytes()