Available on Neko, Android, iOS, macOS, Linux, Windows
o's value and returns the resulting JSON string.
replacer is given and is not null, it is used to retrieve
actual object to be encoded. The
replacer function takes two parameters,
the key and the value being encoded. Initial key value is an empty string.
space is given and is not null, the result will be pretty-printed.
Successive levels will be indented by this string.