title: Python webscraping remove duplicate emails
body: <p>How can I remove duplicate emails from this code?
  Does it work with <code>set()</code>? I tried some things but without luck.</p>
  
  <pre><code>import requests
  from bs4 import BeautifulSoup as soup
  def get_emails(_links:list):
  
  for i in range(len(_links)):
   new_d = soup(requests.get(_links[i]).text, 'html.parser').find_all('a', {'class':'my_modal_open'})
   if new_d:
     yield new_d[-1]['title']
  
  start = 20
  while True:
  d = soup(requests.get('http://www.schulliste.eu/type/gymnasien/?bundesland=&amp;start={page_id}'.format(page_id=start)).text, 'html.parser')
  results = [i['href'] for i in d.find_all('a')][52:-9]
  results = [link for link in results if link.startswith('http://')]
  
  items = list(get_emails(results))
  for item in items:
  
      print(item)
  
  next_page=d.find('div', {'class': 'paging'}, 'weiter')
  
  if next_page:
  
      start+=20
  
  else:
      break
  </code></pre>
  
  <p>Is there a way to just get an email address once?</p>