'Find a record currently stored in this instance by its record ID
@param key: the record ID
@return: a Row
@raises: IndexError if the record is not currently loaded'

def __getitem__(self, key):

    index = self._rowindex
    if (index is None):
        _id = self._id.name
        rows = self._rows
        if rows:
            index = Storage([(str(row[_id]), row) for row in rows])
        else:
            index = Storage()
        self._rowindex = index
    key = str(key)
    if (key in index):
        return index[key]
    raise IndexError
