title: Program that searches for words that use certain letters
body: <p>I'm designing a program that looks through a list of words, and counts how many words only have the letters p, y, t, h, o and n in them.</p>
  
  <p>So far, my code is:</p>
  
  <pre><code>def find_python(string, python):
   """searches for the letters 'python' in the word."""
   for eachLetter in python:
      if eachLetter not in string:
          return False
   return True
  
  def main():
   python = 'python'
   how_many = 0
  
   try:
   fin = open('words.txt')#open the file
   except:
       print("No, no, file no here") #if file is not found
   for eachLine in fin:
      string = eachLine
      find_python(string, python)
  if find_python(string, python) == True:
      how_many = how_many + 1#increment count if word found
   print how_many#print out count
   fin.close()#close the file
  
  if __name__ == '__main__':
  main()
  </code></pre>
  
  <p>However, my code is returning the incorrect number of words, for example, it will return the word 'xylophonist' if I put in the print statement for it because it has the letters python in it. What should I do so it will reject any word that has forbidden letters?</p>