code: def diff_colormap():
      "Custom colormap to map low values to black or another color."
  
      # bottom = plt.cm.copper(np.linspace(0., 1, 6))
      black = np.atleast_2d([0., 0., 0., 1.])
      bottom = np.repeat(black, 6, axis=0)
      middle = plt.cm.copper(np.linspace(0, 1, 250))
      # remain = plt.cm.Reds(np.linspace(0, 1, 240))
  
      colors = np.vstack((bottom, middle))
      diff_colormap = mpl.colors.LinearSegmentedColormap.from_list('diff_colormap', colors)
  
      return diff_colormaf diff_colormap():
      "Custom colormap to map low values to black or another color."
  
      # bottom = plt.cm.copper(np.linspace(0., 1, 6))
      black = np.atleast_2d([0., 0., 0., 1.])
      bottom = np.repeat(black, 6, axis=0)
      middle = plt.cm.copper(np.linspace(0, 1, 250))
      # remain = plt.cm.Reds(np.linspace(0, 1, 240))
  
      colors = np.vstack((bottom, middle))
      diff_colormap = mpl.colors.LinearSegmentedColormap.from_list('diff_colormap', colors)
  
      return diff_colormap
docs: Custom colormap to map low values to black or another color.