def somefx(f, coll):
    """ Returns the first f(x) for x in coll where f(x) is logical true.
        If no such element is found, returns None.

    >>> import string
    >>> somefx(string.strip, ['', '     ', '     Hello ', ' '])
    'Hello'
    >>> somefx(string.strip, ['', '     ', ' '])
    """
    for elem in coll:
        res = f(elem)
        if res:
            return res
    return None