code: def dminus(f):
      r"""Calculate the Minus Directional Movement (-DM).
  
      Parameters
      ----------
      f : pandas.DataFrame
          Dataframe with columns ``high`` and ``low``.
  
      Returns
      -------
      new_column : pandas.Series (float)
          The array containing the new feature.
  
      References
      ----------
      *Directional movement is negative (minus) when the prior low minus
      the current low is greater than the current high minus the prior high.
      This so-called Minus Directional Movement (-DM) equals the prior low
      minus the current low, provided it is positive. A negative value
      would simply be entered as zero* [SC_ADX]_.
  
      """
      c1 = "downmove"
      f[c1] = -net(f, "low")
      c2 = "upmove"
      f[c2] = net(f, "high")
      new_column = f.apply(gtval0, axis=1, args=[c1, c2])
      return new_column
  
imports: from alphapy.calendrical import biz_day_month
  from alphapy.calendrical import biz_day_week
  from alphapy.globals import NULLTEXT
  from alphapy.globals import BSEP, PSEP, USEP
  from alphapy.variables import vexec
  import itertools
  import logging
  import math
  import numpy
  import pandas
label_desc: Use image node_id 9 for calling a global function with example usage: dminus(f) and returns: new_column