'Return the value(s) of the specified row(s).  If ``last`` is
not specified, then return a single row value; otherwise,
return a list of row values.  Each row value is a tuple of
cell values, one for each column in the row.'

def get(self, first, last=None):

    values = [lb.get(first, last) for lb in self._listboxes]
    if last:
        return [tuple(row) for row in zip(*values)]
    else:
        return tuple(values)
