text: from .quantity_type import QuantityType
  from .quantity import Quantity
  from .units import Unit
  from .time import TimeType
  from .angular_velocity import AngularVelocityType
  
  class radian_per_second_squared(Unit):
      profile = {   
          "name":"radian per second squared",
          "symbol":"rad*s-2",
          "express_by_SI_base":"s-2",
          "express_by_SI":""
      }
  
  class AngulaAccelerationType(QuantityType):
      pri_unit = radian_per_second_squared
      SI_conherent_unit = pri_unit
      @classmethod
      def register_type(cls):
          cls.source[(AngularVelocityType, '/', TimeType)] = cls
          cls.source[(cls, '*', TimeType)] = AngularVelocityType
          cls.source[(TimeType, '*', cls)] = AngularVelocityType
          cls.source[(AngularVelocityType, '/', cls)] = TimeType
  class AngulaAcceleration(Quantity):
      def __init__(self, value, unit=None):
          super().__init__(value, AngulaAccelerationType, unit)