input: 
  import numpy as np
  
  def runningTotal(arr):
      """Return an array with the running total of numbers in the given list.
      >>> runningTotal([1, 2, 3, 4])
      array([1, 3, 6, 10])
      >>> runningTotal([5, 6, 7, 8])
      array([ 5, 11, 18, 26])
      """
      return np.cumsum(arr)
  
output:     return np.cumsum(arr)