code: func (c *CNIConfig) ensureExec() invoke.Exec {
  	if c.exec == nil {
  		c.exec = &invoke.DefaultExec{
  			RawExec:       &invoke.RawExec{Stderr: os.Stderr},
  			PluginDecoder: version.PluginDecoder{},
  		}
  	}
  	return c.exec
  }
docs: // ensure we have a usable exec if the CNIConfig was not given one