input: Write a function to return an array with the running total of numbers in a given list using numpy.
  
  def runningTotal(arr):
      return np.cumsum(arr)
  
  assert np.array_equal(runningTotal([1, 2, 3, 4]), [1, 3, 6, 10]) == True
  assert np.array_equal(runningTotal([1, 1, 1, 1]), [1, 2, 3, 4]) == True
  assert np.array_equal(runningTotal([0, 0, 0, 0]), [0, 0, 0, 0]) == True
  assert np.array_equal(runningTotal([-1, 2, -3, 4]), [-1, 1, -2, 2]) == True
  assert np.array_equal(runningTotal([]), []) == True
output: def runningTotal(arr):
      return np.cumsum(arr)