docs: function convertSVGToPNG(source, dest, options) {
      if (!fs.existsSync(source)) return Promise.reject(new error.FileNotFoundError({ filename: source }));
  
      return command.spawn('svgexport', [source, dest])
      .fail(function(err) {
          if (err.code == 'ENOENT') {
              err = error.RequireInstallError({
                  cmd: 'svgexport',
                  install: 'Install it using: "npm install svgexport -g"'
              });
          }
          throw err;
      })
      .then(function() {
          if (fs.existsSync(dest)) return;
  
          throw new Error('Error converting '+source+' into '+dest);
      });
  }