code: function flow(options) {
  	const result = spawnSync(bin, [
  		'check-contents',
  		'--json',
  		`--root=${options.root}`,
  		options.fileName
  	], {
  		input: options.source,
  		encoding: 'utf-8'
  	});
  
  	if (result.status !== 0) {
  		return [{
  			message: result.stderr,
  			loc: {
  				start: {
  					line: 1
  				},
  				end: {
  					line: 1
  				}
  			}
  		}];
  	}
  
  	const {errors} = JSON.parse(result.stdout);
  
  	return errors.map(error => {
  		const [leading, ...rest] = error.message;
  		const payload = rest.map(m => format(m, {
  			root: options.root
  		}));
  
  		return {
  			message: [leading.descr, ...payload].join(': '),
  			path: leading.path,
  			start: leading.loc.start.line,
  			end: leading.loc.end.line,
  			loc: leading.loc
  		};
  	});
  }
docs: start a flow server