class_docstr: 测试每一个 callback 是否在 trainer 中都得到了调用；
class_docstr_tok: ["\u6d4b\u8bd5\u6bcf\u4e00\u4e2a","callback","\u662f\u5426\u5728","trainer","\u4e2d\u90fd\u5f97\u5230\u4e86\u8c03\u7528\uff1b"]
code: def on_before_optimizers_step(self, trainer, optimizers):
      print("on_before_optimizers_step")
  
imports: from fastNLP.core.callbacks.callback import Callback
label_desc: Use image node_id 15 for calling the RecordTrainerEventTriggerCallback obj's underlying member method code with example usage: obj.on_before_optimizers_step(trainer, optimizers) without return types