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