input: 
  import numpy as np
  
  def runningTotal(arr):
      """
      Calculate the running total of numbers in a given list using numpy's cumsum function.
      >>> runningTotal([1, 2, 3, 4])
      array([ 1,  3,  6, 10])
      >>> runningTotal([5, 10, 15])
      array([ 5, 15, 30])
      """
      return np.cumsum(arr)
  
output:     return np.cumsum(arr)