<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def iter_decode(input, fallback_encoding, errors='replace'):
 """ "Pull"-based decoder. :param input: An iterable of byte strings. The input is first consumed just enough to determine the encoding based on the precense of a BOM, then consumed on demand when the return value is. :param fallback_encoding: An :class:`Encoding` object or a label string. The encoding to use if :obj:`input` does note have a BOM. :param errors: Type of error handling. See :func:`codecs.register`. :raises: :exc:`~exceptions.LookupError` for an unknown encoding label. :returns: An ``(output, encoding)`` tuple. :obj:`output` is an iterable of Unicode strings, :obj:`encoding` is the :obj:`Encoding` that is being used. """


    decoder = IncrementalDecoder(fallback_encoding, errors)
    generator = _iter_decode_generator(input, decoder)
    encoding = next(generator)
    return generator, encoding