Comment by TylerE

You don't.

Use generator syntax, which is really the more pythonic way to it.

    >>> iter = [1,2,3,4]
    >>> f1 = lambda x: x*2
    >>> f2 = lambda x: x+4
    >>> f3 = lambda x: x*1.25
    >>> [f3(f2(f1(x))) for x in iter]
    [7.5, 10.0, 12.5, 15.0]