python merge sort

merge_sort.py

def merge_sort(list_struct=[]):
    """
    merge_sort
    as if there's not enough merge sorts in python out there
    """
    list_len = len(list_struct)
    if list_len <= 1:
        return list_struct

    mid = list_len / 2
    left = list_struct[:mid]
    right = list_struct[mid:]

    left = merge_sort(left)
    right = merge_sort(right)
    new_list_struct = []

    while left and right:
        if left[0] < right[0]:
            new_list_struct.append(left.pop(0))
        else:
            new_list_struct.append(right.pop(0))

    if left:
        new_list_struct.extend(left)
    if right:
        new_list_struct.extend(right)

    return new_list_struct