code: def generate_not(self):
          
          not_definition = self._definition['not']
          if not_definition is True:
              self.l('raise JsonSchemaException("{name} must not be there")')
          elif not_definition is False:
              return
          elif not not_definition:
              with self.l('if {}:', self._variable):
                  self.l('raise JsonSchemaException("{name} must not be valid by not definition")')
          else:
              with self.l('try:'):
                  self.generate_func_code_block(not_definition, self._variable, self._variable_name)
              self.l('except JsonSchemaException: pass')
              self.l('else: raise JsonSchemaException("{name} must not be valid by not definition")')
docs: Means that value have not to be valid by this definition.
  
          .. code-block:: python
  
              {'not': {'type': 'null'}}
  
          Valid values for this definition are 'hello', 42, {} ... but not None.
  
          Since draft 06 definition can be boolean. False means nothing, True
          means everything is invalid.