code: def test_linear(self):
      self._run_pass(
          lr_scheduler="linear", warmup_updates=0, end_zero=True
      )
      self._run_pass(
          lr_scheduler="linear", warmup_updates=50, end_zero=True
      )
      with self.assertRaises(lr_scheduler.StopTrainException):
          self._run_pass(
              lr_scheduler="linear",
              max_train_steps=100,
              total_steps=1000,
          )
  
imports: import os
  import unittest
  import torch
  import parlai.nn.lr_scheduler
  import parlai.utils.testing
label_desc: Use image node_id 4 for calling the TestLRSchedulers obj's underlying member method code with example usage: obj.test_linear() without return types