docs: def netloc(self):
          """return username:password@hostname:port"""
          s = ''
          prefix = ''
          if self.username:
              s += self.username
              prefix = '@'
  
          if self.password:
              s += ":{password}".format(password=self.password)
              prefix = '@'
  
          s += "{prefix}{hostloc}".format(prefix=prefix, hostloc=self.hostloc)
          return s