'Allows accessing children by index
:param key:
An integer of the child index
:raises:
KeyError - when an index is invalid
:return:
The Asn1Value object of the child specified'

def __getitem__(self, key):

    if ((key > (len(self._child_specs) - 1)) or (key < 0)):
        raise KeyError(unwrap(u'\n                                                                No    child    is    definition    for    position    %d    of    %s\n                                                                ', key, type_name(self)))
    return self._children[key]
