text: """Defines the Action for the continuous light-dark domain;
  
  Origin: Belief space planning assuming maximum likelihood observations
  
  Action space: 
  
      :math:`U\subseteq\mathbb{R}^2`. Quote from the paper: "The robot is
          modeled as a first-order system such that the robot velocity is determined
          by the control actions, :math:`u\in\mathbb{R}^2`.
  """
  import pomdp_py
  
  class Action(pomdp_py.Action):
      """The action is a vector of velocities"""
      def __init__(self, control):
          """
          Initializes a state in light dark domain.
  
          Args:
              control (tuple): velocity
          """
          if len(control) != 2:
              raise ValueError("Action control must be a vector of length 2")        
          self.control = control
  
      def __hash__(self):
          return hash(self.control)
      
      def __eq__(self, other):
          if isinstance(other, Action):
              return self.control == other.control
          else:
              return False
          
      def __str__(self):
          return self.__repr__()
      
      def __repr__(self):
          return "Action(%s)" % (str(self.control))
          
  