title: Why can I not create a simple loop?
body: <p>I am attempting to create a simple program that reads enzyme cuts from a dna sequence file. My problem is that I cannot get the first block to repeat in a loop. What am I doing wrong so I can turn this into a loop? Any help is greatly appreciated, thanks!!</p>
  
  <pre><code>sequence = open('sequence.txt').read().replace('\n','')
  enzymes = {}
  fh = open('enzymes.txt')
  print('Restriction Enzyme Counter')
  inez = input('Enter a Restricting Enzyme: ')
  def servx():
      for line in fh.readlines():
          (name, site, junk, junk) = line.split()
          enzymes[name] = site 
          if inez in line:
              xcr = site
              print('Active Bases:', site)
      for line in sequence.split():
          if xcr in line:
              bs = (sequence.count(xcr))
              print('Enzyme', inez, 'appears', bs, 'times in Sequence.')
  servx()
  inez = input('Find another Enzyme? [Yes/No]:')
  if inez is 'Yes':
      servx()
  fh.close()
  </code></pre>