code: def _compile_int_f(self):
          
          string = '"""\n'
          string += 'system.dae.init_f()\n'
  
          # evaluate differential equations f
          for fcall, call in zip(self.fcall, self.fcalls):
              if fcall:
                  string += call
          string += 'system.dae.reset_small_f()\n'
          string += '"""'
          self.int_f = compile(eval(string), '', 'exec')
docs: Time Domain Simulation - update differential equations