title: Conceptual error in linguistic python coding
body: <p>For backround: Certain letters in Finnish words are not part of the typical orthography and may indicate that a word originated in another language. These may be proper names in another language, or may be loan words – that is, they are part of the Finnish language but borrowed from another language. Letters that may indicate a word is a loan word are:
  åcqxfgwz</p>
  
  <p>I'm trying to write a program that meets the following specs:
  a function called get_loan_words(filename) that reads in a text file in Finnish and returns a dictionary mapping each letter shown above to the set of loanwords that contain it in the text contained in a text file. If more than one of these letters appears in a word, the set associated with each letter should contain the word. If a letter is not found in any word in the text, it should not appear in the dictionary. The function should convert the text to all lowercase and remove punctuation before creating the dictionary.</p>
  
  <p>For example, if we used the following text (an excerpt from a .txt file):
  Kärppien kasvatti on pelannut SM-liigassa oululaisseuran lisäksi Pelicansin sekä HIFK:n riveissä, mistä lähti viime kauden jälkeen juuri Rögleen. Aaltonen on nelinkertainen Suomen- mestari ja kuusinkertainen SM-mitalisti.SM-liigan ja useiden muiden huippusarjojen siirtoikkuna sulkeutuu ensi viikolla.</p>
  
  <p>The dictionary returned would be:
    {'g': {'smmitalistismliigan', 'smliigassa', 'rögleen'}, 'c': {'pelicansin'}, 'f': {'hifkn'}}</p>
  
  <p>Right now this is the code I have:</p>
  
  <pre><code>def find_loan(filename):
    loans = {}
    LOAN  = 'åcqxfgwz'
    with open(filename,'r',encoding='UTF-8') as entries:
      for line in entries:
  </code></pre>
  
  <p>My questions are as follows:</p>
  
  <ol>
  <li><p>How do I remove punctuation and convert the text to lowercase in the returned dictionary,is there  set methods that does this for all keys/values in a dictionary?</p></li>
  <li><p>How do I make the function add words to the set from the text file and how do I make sure if there is a different loan word letter in a word that the set returns the word twice under a different key value?</p></li>
  </ol>