docs: def add(self, child):
          """
          Adds a typed child object to the behavioral object.
  
          @param child: Child object to be added.
          """
  
          if isinstance(child, StateVariable):
              self.add_state_variable(child)
          elif isinstance(child, DerivedVariable):
              self.add_derived_variable(child)
          elif isinstance(child, ConditionalDerivedVariable):
              self.add_conditional_derived_variable(child)
          elif isinstance(child, TimeDerivative):
              self.add_time_derivative(child)
          elif isinstance(child, EventHandler):
              self.add_event_handler(child)
          elif isinstance(child, KineticScheme):
              self.add_kinetic_scheme(child)
          else:
              raise ModelError('Unsupported child element')