guessing german words with fixed length and given chars

"""
This is a small programm to solve
word guess games with given chars and a given wordlength

Download the dict at: http://extensions.libreoffice.org/extension-center/german-de-de-frami-dictionaries/releases/2013.12.06
Unzip it (change the extension from .ocx to .zip)
You'll need the file de_DE_frami/de_DE_frami.dic
"""

import argparse
import os
import sys
from collections import Counter

def collect(dictionary, num_chars):
    """
    This function collects from a dict-file each
    line and saves it to a set.
    """
    with open(dictionary, 'r') as fd:
        wordlist = set()
        for word in fd:
            if not word.startswith('#'):
                (word, _, _) = word.decode('ISO8859-1').strip().partition('/')
                if len(word) == num_chars:
                    wordlist.add(word)
    return wordlist


def find_matches(allowed_chars, num_chars, wordlist):
    allowed_chars = Counter(allowed_chars.decode('utf8').lower())
    for word in wordlist:
        c_word = Counter(word.lower())
        #print allowed_chars
        diff = c_word & allowed_chars
        if sum(diff.values()) == num_chars:
            yield word

if __name__ == '__main__':
    # example:
    # ./woerter.py -d "/home/deadeye/Downloads/de_DE_frami/de_DE_frami.dic" -c "ZDTTXUCEERME" -n6

    parser = argparse.ArgumentParser(description='Find words from allowed chars and length from a dict')
    parser.add_argument('-n', metavar='word_length', type=int, default=[-1],
                     help='lenght of the word to find',
                     action='store', nargs=1, required=False)
    parser.add_argument('-c', metavar='allowed_chars', type=str,
                        help='allowed chars in a word', action='store', nargs=1, required=True)
    parser.add_argument('-d', metavar='dictionary', type=str,
                        help='dic file from libre office', action='store', nargs=1, required=True)
    args = parser.parse_args()
    if not os.path.isfile(args.d[0]) or not os.access(args.d[0], os.R_OK):
        print "Dictionary is not accessible"
        sys.exit(1)
    if args.n[0] == -1:
        n = len(args.c[0])
    else:
        n = args.n[0]
    if len(args.c[0]) < args.n[0]:
        print "Required chars are less then the required num of chars"
        sys.exit(2)
    wordlist = collect(args.d[0], n)
    matches = find_matches(args.c[0], n, wordlist)
    for match in matches:
        print match