parameters: (self, **attributes)
docstring: Add the items to the instance of the environment if they do not exist
          yet.  This is used by :ref:`extensions <writing-extensions>` to register
          callbacks and configuration values without breaking inheritance.
docstring_summary: Add the items to the instance of the environment if they do not exist
          yet.  This is used by :ref:`extensions <writing-extensions>` to register
          callbacks and configuration values without breaking inheritance.
docstring_tokens: Add the items to the instance of the environment if they do not exist yet . This is used by : ref : extensions <writing - extensions > to register callbacks and configuration values without breaking inheritance .
function: def extend(self, **attributes):
          """Add the items to the instance of the environment if they do not exist
          yet.  This is used by :ref:`extensions <writing-extensions>` to register
          callbacks and configuration values without breaking inheritance.
          """
          for key, value in iteritems(attributes):
              if not hasattr(self, key):
                  setattr(self, key, value)
function_tokens: def extend ( self , * * attributes ) : for key , value in iteritems ( attributes ) : if not hasattr ( self , key ) : setattr ( self , key , value )