code: def __curve_data_filter__(curve):
      """
      Eliminate and refine the points at which the curve is undefined.
  
      :param curve: curve
      :type curve: pycm.Curve object
      :return: None
      """
      none_warning = False
      for c in curve.classes:
          data_temp = {curve.plot_x_axis: [], curve.plot_y_axis: []}
          x_data = curve.data[c][curve.plot_x_axis]
          y_data = curve.data[c][curve.plot_y_axis]
          for x, y in zip(x_data, y_data):
              if x != "None" and y != "None":
                  data_temp[curve.plot_x_axis].append(x)
                  data_temp[curve.plot_y_axis].append(y)
              else:
                  none_warning = True
          curve.data[c] = data_temp
      if none_warning:
          warn(CURVE_NONE_WARNING, RuntimeWarning)
  
imports: from __future__ import division
  from .pycm_error import pycmCurveError, pycmPlotError
  from .pycm_util import threshold_func, thresholds_calc, isfloat
  from .pycm_param import *
  from .pycm_obj import ConfusionMatrix
  from warnings import warn
  import numpy
label_desc: Use image node_id 5 for calling a global function with example usage: __curve_data_filter__(curve) without return types