docstr: Tell the moving average tracker which parameters we are going to track.
  
  Parameters
  ----------
  params : ParameterDict
      The parameters that we are going to track and calculate the moving average.
docstr_tok: ["Tell","the","moving","average","tracker","which","parameters","we","are","going","to","track",".","Parameters","--","--","--","--","--","params",":","ParameterDict","The","parameters","that","we","are","going","to","track","and","calculate","the","moving","average","."]
code: def apply(self, params):
      """Tell the moving average tracker which parameters we are going to track.
  
      Parameters
      ----------
      params : ParameterDict
          The parameters that we are going to track and calculate the moving average.
      """
      assert self._track_params is None, (
          "The MovingAverageTracker is already initialized and"
          " is not allowed to be initialized again. "
      )
      self._track_params = deduplicate_param_dict(params)
      self._n_steps = 0
  
imports: import warnings
  import numpy
  import mxnet
  from collections import defaultdict
  from mxnet.gluon import Parameter
  from mxnet.util import use_np
  from typing import Iterable, Optional, Tuple
  from collections import OrderedDict
  from mxnet.gluon.utils import shape_is_known
label_desc: Use image node_id 5 for calling the AverageSGDTracker obj's underlying member method code with example usage: obj.apply(params) without return types