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// modified from vega-cli
const vega = require('vega');const path = require('path');const args = require('./args');const read = require('./read');const vegaLite = require('..');
function load(file) {  return require(path.resolve(file));}
const Levels = {  error: vega.Error,  warn: vega.Warn,  info: vega.Info,  debug: vega.Debug};
module.exports = function (type, callback, opt) {  // parse command line arguments  const arg = args(type);
  // set baseURL, if specified. default to input spec directory  const base = arg.base || (arg._[0] ? path.dirname(arg._[0]) : null);
  // set log level, defaults to logging warning messages  const loglevel = Levels[String(arg.loglevel).toLowerCase()] || vega.Warn;
  // load config file, if specified  const config = arg.config ? load(arg.config) : null;
  // set output image scale factor  const scale = arg.scale || undefined;
  // use a seeded random number generator, if specified  if (typeof arg.seed !== 'undefined') {    if (Number.isNaN(arg.seed)) throw 'Illegal seed value: must be a valid number.';    vega.setRandom(vega.randomLCG(arg.seed));  }
  // locale options, load custom number/time formats if specified  const locale = {    number: arg.format ? load(arg.format) : null,    time: arg.timeFormat ? load(arg.timeFormat) : null  };
  // instantiate view and invoke headless render method  function render(vlSpec) {    const vgSpec = vegaLite.compile(vlSpec).spec;    const view = new vega.View(vega.parse(vgSpec, config), {      locale: locale, // set locale options      loader: vega.loader({baseURL: base}), // load files from base path      logger: vega.logger(loglevel, 'error'), // route all logging to stderr      renderer: 'none' // no primary renderer needed    }).finalize(); // clear any timers, etc
    return (type === 'svg' ? view.toSVG(scale) : view.toCanvas(scale, opt)).then(_ => callback(_, arg));  }
  // read input from file or stdin  read(arg._[0] || null)    .then(text => render(JSON.parse(text)))    .catch(err => console.error(err)); // eslint-disable-line no-console};