Time Sort in Python

def insertion_sort(array, left=0, right=None):
    if right is None:
        right = len(array) - 1

    # Loop from the element indicated by
    # `left` until the element indicated by `right`
    for i in range(left + 1, right + 1):
        # This is the element we want to position in its
        # correct place
        key_item = array[i]

        # Initialize the variable that will be used to
        # find the correct position of the element referenced
        # by `key_item`
        j = i - 1

        # Run through the list of items (the left
        # portion of the array) and find the correct position
        # of the element referenced by `key_item`. Do this only
        # if the `key_item` is smaller than its adjacent values.
        while j >= left and array[j] > key_item:
            # Shift the value one position to the left
            # and reposition `j` to point to the next element
            # (from right to left)
            array[j + 1] = array[j]
            j -= 1

        # When you finish shifting the elements, position
        # the `key_item` in its correct location
        array[j + 1] = key_item

    return array