static isSourceMap(input) {
    // All required options for `new TraceMap(...options)`
    // https://github.com/jridgewell/trace-mapping#usage
    return Boolean(
      input &&
        input.version &&
        input.sources &&
        Array.isArray(input.sources) &&
        typeof input.mappings === "string"
    );
  }
@private
@param {any} input
@returns {boolean}