input: 
  import numpy as np
  
  def runningTotal(arr):
      """ Calculate the running total of numbers in a given list using numpy.
      >>> runningTotal([1, 2, 3, 4])
      array([ 1,  3,  6, 10])
      >>> runningTotal([5, -2, 3, 1])
      array([ 5,  3,  6,  7])
      """
      return np.cumsum(arr)
  
output:     return np.cumsum(arr)