code: def units(cls, scale=1):
          '''
          :scale: optional integer scaling factor
          :return: list of three Point subclass
  
          Returns three points whose coordinates are the head of a
          unit vector from the origin ( conventionally i, j and k).
  
          '''
          return [cls(x=scale), cls(y=scale), cls(z=scale)f units(cls, scale=1):
          '''
          :scale: optional integer scaling factor
          :return: list of three Point subclass
  
          Returns three points whose coordinates are the head of a
          unit vector from the origin ( conventionally i, j and k).
  
          '''
          return [cls(x=scale), cls(y=scale), cls(z=scale)]
docs: :scale: optional integer scaling factor
          :return: list of three Point subclass
  
          Returns three points whose coordinates are the head of a
          unit vector from the origin ( conventionally i, j and k).