code: def absolute_error(y, yhat):
      """Returns the maximal absolute error between y and yhat.
  
      :param y: true function values
      :param yhat: predicted function values
  
      Lower is better.
  
      >>> absolute_error([0,1,2,3], [0,0,1,1])
      2.0
  
      """
      return float(max(map(lambda x, y: math.fabs(x - y), y, yhat)))
  
imports: import math
  import operator
label_desc: Use image node_id 9 for calling a global function with example usage: absolute_error(y, yhat) and returns: float