Make comments more useful

content.go

@@ -14,7 +14,10 @@ type Content interface {
 	Check() error
 }
 
-// NewContent creates a new Content. It returns a Content and an error.
+// NewContent creates a new Content. It takes in an int contentType, a string
+// mediaType and an any content and returns a Content.
+//
+// If contentType is invalid, it returns nil.
 func NewContent(contentType int, mediaType string, content any) Content {
 	switch contentType {
 	case 0: