#! /usr/bin/python

""" Module email2 
Contains a single function extract_email_addr() that returns a sorted
list of the uniue email addresses found in the string which is it's
single argument.  

If called as a script, it applies this function to the text from stdin
and then prints the email addresses found to stdout, one to a line
"""

import re
from sys import stdin

# this pattern approximates a legal email address
pat = re.compile(r'[-\w][-.\w]*@[-\w][-\w.]+[a-zA-Z]{2,4}')

def extract_email_addr(text):

    """returns a sorted list of the uniue email addresses found in the
    string which is it's single argument"""

    found = set()

    for address in pat.findall(text):
        # the add() method adds an element to a set object
        found.add(address)

    return sorted(found)

def main():
    # invoke this if called from a script to get text from stdin and
    # print output to stdout
    for address in extract_email_addr(stdin.read()):
        print address
    
# This will be true of the file was called as a script
if __name__ == "__main__":
    main()