input: Write a function to sort a list of numbers using the Insertion Sort algorithm in Python. The function should take a list of integers as input and return the sorted list in ascending order.
  assert insertionSort([2, 4, 7, 3, 8, 6, 1])==[1, 2, 3, 4, 6, 7, 8]
  assert insertionSort([9, 5, 2, 6, 3, 8, 4])==[2, 3, 4, 5, 6, 8, 9]
  assert insertionSort([])==[]
output: def insertionSort(arr):
      for i in range(1, len(arr)):
          key = arr[i]
          j = i - 1
          while j >= 0 and key < arr[j]:
              arr[j + 1] = arr[j]
              j -= 1
          arr[j + 1] = key
      return arr