input: Write a function to sort a given list of numbers using the Insertion Sort algorithm in Python. The function should return the sorted list. If the list is empty, the function should return an empty 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([9, 5, 3, 7, 2]) == [2, 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