code: def _parse_mtu(self, config):
          
          match = re.search(r'mtu (\d+)', config)
          return dict(mtu=int(match.group(1)))
docs: Parses the config block and returns the configured IP MTU value
  
          The provided configuration block is scanned and the configured value
          for the IP MTU is returned as a dict object.  The IP MTU value is
          expected to always be present in the provided config block
  
          Args:
              config (str): The interface configuration block to parse
  
          Return:
              dict: A dict object intended to be merged into the resource dict