code: def initialize_slot(obj, name, value):
      
      if not hasattr(obj, name):
          object_setattr(obj, name, value)
docs: Initalize an unitialized slot to a value.
  
      If there is already a value for this slot, this is a nop.
  
      Parameters
      ----------
      obj : immutable
          An immutable object.
      name : str
          The name of the slot to initialize.
      value : any
          The value to initialize the slot to.