input: 
  import numpy as np
  
  def runningTotal(arr):
      """ Return an array containing the running total of the numbers in the given list.
      >>> runningTotal([1, 2, 3, 4])
      array([ 1,  3,  6, 10])
      >>> runningTotal([10, 20, 30])
      array([10, 30, 60])
      """
      return np.cumsum(arr)
  
output:     return np.cumsum(arr)