def unrank_from_list(l):
    """
    Returns an unrank function from a list.

    EXAMPLES::

        sage: import sage.combinat.ranker as ranker
        sage: l = [1,2,3]
        sage: u = ranker.unrank_from_list(l)
        sage: u(2)
        3
        sage: u(0)
        1
    """
    unrank = lambda j: l[j]
    return unrank