code: def post(cond):
      
      source = inspect.getsource(cond).strip()
  
      def inner(f):
          if enabled:
              # deal with the real function, not a wrapper
              f = getattr(f, 'wrapped_fn', f)
  
              def check_condition(result):
                  if not cond(result):
                      raise AssertionError('Postcondition failure, %s' % source)
  
              # append to the rest of the postconditions attached to this method
              if not hasattr(f, 'postconditions'):
                  f.postconditions = []
              f.postconditions.append(check_condition)
  
              return check(f)
          else:
              return f
  
      return inner
docs: Add a postcondition check to the annotated method. The condition
       is passed the return value of the annotated method.