def _compile_pfload(self):
        """Post power flow computation for load
                  S_gen  + S_line + [S_shunt  - S_load] = 0
        """
        string = '"""\n'
        string += 'system.dae.init_g()\n'
        for gcall, pflow, shunt, stagen, call in zip(
                self.gcall, self.pflow, self.shunt, self.stagen, self.gcalls):
            if gcall and pflow and shunt and not stagen:
                string += call
        string += '\n'
        string += 'system.dae.reset_small_g()\n'
        string += '"""'
        self.pfload = compile(eval(string), '', 'exec')