old_contents: from flask_babel import gettext
  import re
  from urlparse import urlparse, parse_qsl
  
  regex = re.compile(r'10\.\d{4,9}/[^\s]+')
  
  name = gettext('DOAI rewrite')
  description = gettext('Avoid paywalls by redirecting to open-access versions of publications when available')
  default_on = False
  
  
  def extract_doi(url):
      match = regex.search(url.path)
      if match:
          return match.group(0)
      for _, v in parse_qsl(url.query):
          match = regex.search(v)
          if match:
              return match.group(0)
      return None
  
  
  def on_result(request, search, result):
      doi = extract_doi(result['parsed_url'])
      if doi and len(doi) < 50:
          for suffix in ('/', '.pdf', '/full', '/meta', '/abstract'):
              if doi.endswith(suffix):
                  doi = doi[:-len(suffix)]
          result['url'] = 'http://doai.io/' + doi
          result['parsed_url'] = urlparse(ctx['result']['url'])
      return True
  
new_contents: from flask_babel import gettext
  import re
  from urlparse import urlparse, parse_qsl
  
  regex = re.compile(r'10\.\d{4,9}/[^\s]+')
  
  name = gettext('DOAI rewrite')
  description = gettext('Avoid paywalls by redirecting to open-access versions of publications when available')
  default_on = False
  
  
  def extract_doi(url):
      match = regex.search(url.path)
      if match:
          return match.group(0)
      for _, v in parse_qsl(url.query):
          match = regex.search(v)
          if match:
              return match.group(0)
      return None
  
  
  def on_result(request, search, result):
      doi = extract_doi(result['parsed_url'])
      if doi and len(doi) < 50:
          for suffix in ('/', '.pdf', '/full', '/meta', '/abstract'):
              if doi.endswith(suffix):
                  doi = doi[:-len(suffix)]
          result['url'] = 'http://doai.io/' + doi
          result['parsed_url'] = urlparse(result['url'])
      return True
  
subject: rewrite missing variable