'Saves the current output settings onto a stack.  See
:meth:`pop_output` for more details as to why you would use
this.'

def push_output(self):

    o = {}
    for k in ('separator', 'header', 'nullvalue', 'output', 'widths', 'truncate'):
        o[k] = getattr(self, k)
    self._output_stack.append(o)
