code: func ContentType(typ string) {
  	if mt, ok := mediaTypeDefinition(); ok {
  		mt.ContentType = typ
  	}
  }
docs: // ContentType can be used in: MediaType
  //
  // ContentType sets the value of the Content-Type response header. By default the ID of the media
  // type is used.
  //
  //    ContentType("application/json")
  //