title: Why is it printing both 'username found' and 'username not found'?
body: <pre><code>database=[['username1','password1'],['username2','password2']]
  
  def get_username():
    username= input('enter username:')
    return username
  
  def check_username():
    username=get_username() 
    for pair in database:
      if username==pair[0]:
        print('username found!')
      else:
        print('username not found.')
  </code></pre>
  <p>ouput:</p>
  <pre><code>enter username: username1
         username found!
         username not found.
  </code></pre>