old_contents: const xo = require('xo');
  const path = require('path');
  const assign = require('object-assign');
  
  module.exports = function () {
    this.xo = function (opts) {
      opts = assign({quiet: false}, opts);
      const proj = this.root;
  
      return xo.lintFiles(this._.globs, opts).then(report => {
        // truncate project root from path
        var results = report.results.map(entry => {
          entry.filePath = path.relative(proj, entry.filePath);
          return entry;
        });
  
        // hide warnings
        if (opts.quiet) {
          results = xo.getErrorResults(results);
        }
  
        if (report.errorCount > 0 || report.warningCount > 0) {
          this.log(xo.getFormatter()(results));
        }
  
        if (report.errorCount > 0) {
          const end = (results.length > 1) ? 'files!' : 'file!';
  
          this.emit('plugin_error', {
            plugin: 'fly-xo',
            error: 'XO found '+ report.errorCount +' errors in '+ results.length +' '+end
          });
        }
      });
    };
  };
  
new_contents: const xo = require('xo');
  const path = require('path');
  const assign = require('object-assign');
  
  module.exports = function () {
    this.xo = function (opts) {
      opts = assign({quiet: false}, opts);
      const proj = this.root;
  
      return xo.lintFiles(this._.globs, opts).then(report => {
        // truncate project root from path
        var results = report.results.map(entry => {
          entry.filePath = path.relative(proj, entry.filePath);
          return entry;
        });
  
        // hide warnings
        if (opts.quiet) {
          results = xo.getErrorResults(results);
        }
  
        if (report.errorCount > 0 || report.warningCount > 0) {
          this.log(xo.getFormatter()(results));
        }
  
        if (report.errorCount > 0) {
          const end = (results.length > 1) ? 'files!' : 'file!';
          const num = results.filter(el => el.errorCount > 0).length;
  
          this.emit('plugin_error', {
            plugin: 'fly-xo',
            error: 'XO found '+ report.errorCount +' errors in '+ num +' '+end
          });
        }
      });
    };
  };
  
subject: fix files count