old_contents: from ..system import QuantumSystem
  
  class SimpleQuantumSystem(QuantumSystem):
  
      def setup_environment(self, **kwargs):
          '''
          Configure any custom properties/attributes using kwargs passed
          to __init__.
          '''
          self.kwargs = kwargs
  
      def setup_parameters(self):
          '''
          After the QuantumSystem parameter initialisation routines
          are run, check that the parameters are initialised correctly.
          '''
          pass
  
      def setup_bases(self):
          '''
          Add the bases which are going to be used by this QuantumSystem
          instance.
          '''
          pass
  
      def setup_hamiltonian(self):
          '''
          Initialise the Hamiltonian to be used by this QuantumSystem
          instance.
          '''
          return self.Operator(self.kwargs['hamiltonian'])
  
      def setup_states(self):
          '''
          Add the named/important states to be used by this quantum system.
          '''
          pass
  
      def setup_measurements(self):
          '''
          Add the measurements to be used by this quantum system instance.
          '''
          for name,meas in self.kwargs.get('measurements',{}).items():
              self.add_measurement(name, meas)
  
      @property
      def default_derivative_ops(self):
          return ['evolution']+self.get_derivative_ops().keys()
  
      def get_derivative_ops(self, components=None):
          '''
          Setup the derivative operators to be implemented on top of the
          basic quantum evolution operator.
          '''
          return self.kwargs.get('operators',{})
  
new_contents: from ..system import QuantumSystem
  
  class SimpleQuantumSystem(QuantumSystem):
  
      def setup_environment(self, **kwargs):
          '''
          Configure any custom properties/attributes using kwargs passed
          to __init__.
          '''
          self.kwargs = kwargs
  
      def setup_parameters(self):
          '''
          After the QuantumSystem parameter initialisation routines
          are run, check that the parameters are initialised correctly.
          '''
          pass
  
      def setup_bases(self):
          '''
          Add the bases which are going to be used by this QuantumSystem
          instance.
          '''
          pass
  
      def setup_hamiltonian(self):
          '''
          Initialise the Hamiltonian to be used by this QuantumSystem
          instance.
          '''
          return self.Operator(self.kwargs['hamiltonian'])
  
      def setup_states(self):
          '''
          Add the named/important states to be used by this quantum system.
          '''
          pass
  
      def setup_measurements(self):
          '''
          Add the measurements to be used by this quantum system instance.
          '''
          for name,meas in self.kwargs.get('measurements',{}).items():
              self.add_measurement(name, meas)
  
      @property
      def default_derivative_ops(self):
          return ['evolution']+self.get_derivative_ops().keys()
  
      def setup_derivative_ops(self, components=None):
          '''
          Setup the derivative operators to be implemented on top of the
          basic quantum evolution operator.
          '''
          for name, op in self.kwargs.get('operators',{}).items():
              self.add_derivative_op(name, op)
  
subject: Fix SimpleQuantumSystem