code: def get_param(self, param, default=None):
          
          if param in self.config:
              return self.config[param]
          elif default is not None:
              return default
          else:
              raise MissingParameter('ppolicy', param)
docs: Get a parameter in config (handle default value)
  
          :param param: name of the parameter to recover
          :type param: string
          :param default: the default value, raises an exception
              if param is not in configuration and default
              is None (which is the default value).
          :type default: string or None
          :rtype: the value of the parameter or the default value if
              not set in configuration