def remove_empties(seq):
    """ Remove items of length 0

    >>> remove_empties([1, 2, ('empty', np.nan), 4, 5])
    [1, 2, 4, 5]

    >>> remove_empties([('empty', np.nan)])
    [nan]

    >>> remove_empties([])
    []
    """
    if not seq:
        return seq

    seq2 = [x for x in seq
              if not (isinstance(x, tuple) and x and x[0] == 'empty')]
    if seq2:
        return seq2
    else:
        return [seq[0][1]]