class_docstr: Class for averaging note evaluations.
docstr: Standard deviation of the errors.
docstr_tok: ["Standard","deviation","of","the","errors","."]
code: def std_error(self):
      """Standard deviation of the errors."""
      warnings.warn(
          "std_error is given for all notes, this will change!"
      )
      return np.nanmean([e.std_error for e in self.eval_objects])
  
imports: from __future__ import absolute_import, division, print_function
  import warnings
  import numpy
  from .None import evaluation_io, MultiClassEvaluation, SumEvaluation, MeanEvaluation
  from .onsets import onset_evaluation, OnsetEvaluation
  from ..io import load_notes
label_desc: Use image node_id 2 for calling the NoteMeanEvaluation obj's underlying member method code with example usage: obj.std_error() and returns: np