code: def cost5x1(x, axis=None):
      """a 5x1 test function, using axis
  
      For example:
        >>> cost5x1([1,2,3,4,5], axis=None)
        [13.922847983320086]
        >>> cost5x1([1,2,3,4,5], axis=0)
        13.922847983320086
      """
      y = function5x1(x)
      return y if axis is None else y[axis]
  
label_desc: Use image node_id 4 for calling a global function with example usage: cost5x1(x, axis) and returns: unknown