code: def PartialDynamicSystem(self, ieq, variable):
          
          if ieq == 0:
              # v=Rw
              if variable == self.physical_nodes[0].variable:
                  # W=V/r
                  return[Gain(self.physical_nodes[1].variable, variable, 1/self.wheels_radius)]
              elif variable == self.physical_nodes[1].variable:
                  # V=rw
                  return[Gain(self.physical_nodes[0].variable, variable, self.wheels_radius)]
          elif ieq == 1:
              # C=-FR
              if variable == self.variables[0]:
                  # C=-FR
                  return[Gain(self.variables[1], variable, -self.wheels_radius)]
              elif variable == self.variables[1]:
                  # F=-C/R
                  return[Gain(self.variables[0], variable, -1/self.wheels_radius)]
docs: returns dynamical system blocks associated to output variable