input: Write a function to compute the running total of numbers in a given list using numpy. The function should return an array with the cumulative sum of the elements in the input list.
  
  import numpy as np
  
  def runningTotal(arr):
      return np.cumsum(arr)
  
  assert np.array_equal(runningTotal([1, 2, 3, 4]), [1, 3, 6, 10])
  assert np.array_equal(runningTotal([5, 10, 15, 20]), [5, 15, 30, 50])
  assert np.array_equal(runningTotal([0, 0, 0, 0]), [0, 0, 0, 0])
  assert np.array_equal(runningTotal([-1, -2, -3]), [-1, -3, -6])
  assert np.array_equal(runningTotal([]), [])
output: 
  def runningTotal(arr):
      return np.cumsum(arr)
  