code: def define(self, value, lineno, namespace=None):
          
          if self.defined:
              error(lineno, "label '%s' already defined at line %i" % (self.name, self.lineno))
  
          self.value = value
          self.lineno = lineno
          self.namespace = NAMESPACE if namespace is None else namespace
docs: Defines label value. It can be anything. Even an AST