code: func OnlyContentTypes(types ...string) Option {
  	return func(c *options) error {
  		if len(types) == 0 {
  			c.contentTypes = nil
  			return nil
  		}
  		c.contentTypes = types
  		return nil
  	}
  }
docs: // OnlyContentTypes allows to specify specific content types to encode.
  // Overrides previous content types.
  // no types = ignore content types (always compress).