parameters: (self, name)
docstring: Register a special name like `loop`.
docstring_summary: Register a special name like `loop`.
docstring_tokens: Register a special name like loop .
function: def add_special(self, name):
          """Register a special name like `loop`."""
          self.undeclared.discard(name)
          self.declared.add(name)
function_tokens: def add_special ( self , name ) : self . undeclared . discard ( name ) self . declared . add ( name )