import re


def natural_sort(list, key=lambda s: s):
  """
  Sort the list into natural alphanumeric order.
  """

  def get_alphanum_key_func(key):
    convert = lambda text: int(text) if text.isdigit() else text
    return lambda s: [convert(c) for c in re.split('([0-9]+)', key(s))]

  sort_key = get_alphanum_key_func(key)
  list.sort(key=sort_key)