code: func (c *Configure) option(value interface{}, name string, def interface{}, description string, typ valueType) {
  	opt := &option{
  		name:        name,
  		def:         def,
  		description: description,
  		typ:         typ,
  		value:       value,
  	}
  
  	c.options[name] = opt
  }
docs: // option will bind a pointer to a value provided in the value parameter to
  // set flag value.