text: #!/usr/bin/env python
  
  
  class BLACKBOARD_CONSTANT(object):
      
      __slots__ = ('valyu','boolean','locked')
      
      def __init__(self,value,boolee=True):
          object.__init__(self)
          privates = {'value': value,'boolean':bool(boolee)}
          #value = value
          #boolean = bool(boolean)
          #self.locked=True
          
          def valyu():
              return privates['value']
          self.valyu = valyu
          
          def boolean():
              return privates['boolean']
          self.boolean = boolean
          
          self.locked = 1
      
      def __str__(self):
          return self.valyu()
      def __repr__(self):
          return self.valyu()
      def __hash__(self):
          return hash(self.valyu())
      def __eq__(self,other):
          if type(other) is BLACKBOARD_CONSTANT:
              return self.__hash__() == hash(other.valyu())
          else:
              return self.valyu()==other
      def __ne__(self,other):
          return not self.__eq__(other)
      def __nonzero__(self):
          return self.boolean()
      def __setattr__(self,name,value):
          try:
              _ = self.locked
          except AttributeError:
              object.__setattr__(self,name,value)
              return
          raise AttributeError("Cannot change constant")
      
      def __delattr__(self,name):
          raise AttributeError("Cannot delete constant attributes")
      
  
  NOT_LOGGED_IN=BLACKBOARD_CONSTANT("NOT_LOGGED_IN",False)
  NA=BLACKBOARD_CONSTANT("N/A")
  
  __all__ = ['NOT_LOGGED_IN','NA']
  