val normalize : string -> utf8 * bool
normalize str
take a possibly invalid utf-8 string and return a valid utf-8 string where invalid bytes have been replaced by the replacement character U+FFFD
. The returned boolean is true if invalid bytes were found
val normalize_html : string -> utf8 * bool
Same as normalize
plus some extra work : It encode '<' , '>' , '"' , '&' characters with corresponding entities and replaced invalid html character by U+FFFD