'With one argument, returns a dictionary of column/value pairs
for the specified item. With two arguments, returns the current
value of the specified column. With three arguments, sets the
value of given column in given item to the specified value.'

def set(self, item, column=None, value=None):

    res = self.tk.call(self._w, 'set', item, column, value)
    if ((column is None) and (value is None)):
        return _dict_from_tcltuple(res, False)
    else:
        return res
