code: def warning_implicit_type(lineno, id_, type_=None):
      
      if OPTIONS.strict.value:
          syntax_error_undeclared_type(lineno, id_)
          return
  
      if type_ is None:
          type_ = global_.DEFAULT_TYPE
  
      warning(lineno, "Using default implicit type '%s' for '%s'" % (type_, id_))
docs: Warning: Using default implicit type 'x'