code: def __parse_aliases_stream(self, stream):
          
          if not stream:
              return
  
          f = self.__parse_aliases_line
  
          for alias_entries in self.__parse_stream(stream, f):
              alias = alias_entries[0]
              username = alias_entries[1]
  
              self.__raw_aliases[alias] = username
docs: Parse aliases stream.
  
          The stream contains a list of usernames (they can be email addresses
          their username aliases. Each line has a username and an alias separated
          by tabs. Comment lines start with the hash character (#).
  
          Example:
  
          # List of email aliases
          jsmith@example.com    jsmith@example.net
          jsmith@example.net    johnsmith@example.com
          jdoe@example.com      john_doe@example.com
          jdoe@example          john_doe@example.com