Function json_calc 

pub fn json_calc(query: &str) -> String

Format, validate, pretty-print, query, and diff JSON — instant, no model.

Commands: format <json> — pretty-print with 2-space indentation validate <json> — report valid/invalid with first error location minify <json> — collapse to single line query <path> <json> — extract a value by dot-path (e.g. query a.b[1] {...}) keys <json> — list all top-level keys of an object diff <json1> --- <json2> — show structural differences between two JSON values bare <json> — auto-detects and pretty-prints