'Call the ``mace4`` binary with the given input.
:param input_str: A string whose contents are used as stdin.
:param args: A list of command-line arguments.
:return: A tuple (stdout, returncode)
:see: ``config_prover9``'

def _call_mace4(self, input_str, args=[], verbose=False):

    if (self._mace4_bin is None):
        self._mace4_bin = self._find_binary('mace4', verbose)
    updated_input_str = ''
    if (self._end_size > 0):
        updated_input_str += ('assign(end_size,    %d).\n\n' % self._end_size)
    updated_input_str += input_str
    return self._call(updated_input_str, self._mace4_bin, args, verbose)
