def labelize_flip(couple):
    """
    Returns a string from a 2-uple couple of the form (name, flip).

    TESTS::

        sage: from surface_dynamics.interval_exchanges.reduced import labelize_flip
        sage: labelize_flip((4,1))
        ' 4'
        sage: labelize_flip(('a',-1))
        '-a'
    """
    if couple[1] == -1:
        return '-' + str(couple[0])
    return ' ' + str(couple[0])
