'Look up an item in the submapping for this L{CallMapping}, calling it
if C{key} ends with C{"()"}.'

def __getitem__(self, key):

    callit = key.endswith(u'()')
    realKey = (key[:(-2)] if callit else key)
    value = self._submapping[realKey]
    if callit:
        value = value()
    return value
