#! /usr/bin/python

## Note: load into python with
## import f0830
## or, to avoid module prefix,
## from f0830 import *

# This is a comment
# define a list comprising 10 digits
digits = range(10)


# define a function, num_to_word, which takes a single digit, num,
# and returns the corresponding English word
# ----------------------------------------------------------------
def num_to_word(num):
    if num > 9:
        return False
    numbers = ["zero","one","two","three","four","five","six","seven","eight","nine"]
    return numbers[num]

# define a function, word_to_num, which is the inverse of num-to-word
# Note that we define a sub-function within the function itself.
# The sub-function, find-index, is recursive.
# -------------------------------------------------------------------
def word_to_num(word):
    numbers = ["zero","one","two","three","four","five","six","seven","eight","nine"]
    def find_index(lst,n, word):
        if not lst:
            return False
        if lst[0] == word:
            return n
        return find_index(lst[1:], n+1, word)
    return find_index(numbers,0,word)


# test out the functions

x = map(num_to_word,digits)

xlist = list(x)

y = xlist[:]
y.sort()

z = map(word_to_num,y)

zlist = list(z)

print ("end of f0830")
print ('name: ' + __name__)