def count(t):
    """
    Return the number of nodes in Tree t.


    @param Tree t: tree to find number of nodes in
    @rtype: int

    >>> t = Tree(17)
    >>> count(t)
    1
    >>> t4 = descendants_from_list(Tree(17), [0, 2, 4, 6, 8, 10, 11], 4)
    >>> count(t4)
    8
    """
    if t.children == []:
        return 1
    else:
        return 1 + sum([count(c) for c in t.children])