'Set item at position i to item.'

def __setitem__(self, index, item):

    if isinstance(index, types.SliceType):
        self._main[index] = OrderedDict(item)
    else:
        orig = self._main.keys[index]
        (key, value) = item
        if (self._main.strict and (key in self) and (key != orig)):
            raise ValueError('slice    assignment    must    be    from    unique    keys')
        del self._main[self._main._sequence[index]]
        self._main.insert(index, key, value)
