docstr: Converts continuous values into colors using matplotlib colorscales
  :param cmap_name: colormap name
  :param alpha: color alpha
  :param levels: discretize the colorscale into levels
code: def __init__(self, cmap_name, alpha=255, levels=10):
      """
      Converts continuous values into colors using matplotlib colorscales
      :param cmap_name: colormap name
      :param alpha: color alpha
      :param levels: discretize the colorscale into levels
      """
      from pylab import get_cmap
  
      self.cmap = get_cmap(cmap_name)
      self.alpha = alpha
      self.levels = levels
      self.mapping = {}
  
file_path: geoplotlib/geoplotlib/colors.py
imports: from random import shuffle
  import math
label_desc: Use image node_id 1 to create a new ColorMap object  with example: obj = ColorMap(cmap_name, alpha, levels)