code: def find_emails_by_subject(self, subject, limit=50, match_recipient=None):
          
          # Select inbox to fetch the latest mail on server.
          self._mail.select("inbox")
  
          matching_uids = self.__search_email_by_subject(
              subject, match_recipient)
  
          return matching_uids
docs: Searches for Email by Subject.  Returns email's imap message IDs 
          as a list if matching subjects is found.
  
          Args:
              subject (str) - Subject to search for.
  
          Kwargs:
              limit (int) - Limit search to X number of matches, default 50
              match_recipient (str) - Recipient to exactly (don't care if not specified)
  
          Returns:
              list - List of Integers representing imap message UIDs.