input: Write a function to calculate and return the running total of numbers in a given list using numpy. The function should take an array as input and return an array where each element is the cumulative sum of the elements up to that index in the input array.
  assert runningTotal([1, 2, 3, 4])==[1, 3, 6, 10]
  assert runningTotal([10, 20, 30, 40])==[10, 30, 60, 100]
  assert runningTotal([5])==[5]
  assert runningTotal([0, 0, 0, 0])==[0, 0, 0, 0]
  assert runningTotal([])==[]
output: import numpy as np
  
  def runningTotal(arr):
      return np.cumsum(arr)