input: Write a function that takes a list of numbers as input and returns an array with the running total of the numbers in the given list using numpy. The function should be named `runningTotal`.
  
  
  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([2, 4, 6, 8]), [2, 6, 12, 20])
  assert np.array_equal(runningTotal([]), [])
  assert np.array_equal(runningTotal([5, -1, 0, 2]), [5, 4, 4, 6])
  
output: def runningTotal(arr):
      return np.cumsum(arr)