title: Extract timezone from string
body: <p>Follow up to: <a href="https://stackoverflow.com/questions/20956568/convert-a-list-of-sample-dates-into-gmt">Convert a list of sample dates into GMT</a>?</p>
  
  <p>I have some date samples:
  Like: </p>
  
  <pre><code>Mon, 21 Nov 94 04:28:18 CST 
  dec 21 94 17:05 BST
  </code></pre>
  
  <p>I want to convert this into GMT. For first example it should print:</p>
  
  <pre><code>1994-11-21 10:28:18 
  </code></pre>
  
  <p>Right now it is printing:</p>
  
  <pre><code>1994-11-21 04:28:18
  </code></pre>
  
  <p>I tried this:</p>
  
  <pre><code>from dateutil import parser
  import pytz
  import datetime
  
  def to_utc(dt):
      try:
         return dt.astimezone(pytz.utc)
      except ValueError:
         return pytz.utc.localize(dt)
  
  DEFAULT_DATE = datetime.datetime(datetime.datetime.now().year, 1, 1)
  
  file = open("date_time.txt",'rb')
  
  for line in file:
      date = line.rstrip('\n')
      print date
  
      dt = parser.parse(date, default=DEFAULT_DATE)
      in_utc = to_utc(dt)
      print in_utc
  </code></pre>