old_contents: const gulp = require('gulp')
  const lost = require('lost')
  const cssnano = require('cssnano')
  const mqpacker = require('css-mqpacker')
  const scss = require('postcss-scss')
  const nested = require('postcss-nested')
  const cssnext = require('postcss-cssnext')
  const atImport = require('postcss-import')
  const postcss = require('gulp-postcss')
  
  gulp.task('css', () => {
    var processors = [
      atImport,
      cssnext({ browsers: ['last 2 version'] }),
      lost,
      nested,
      mqpacker,
      cssnano({ autoprefixer: false })
    ]
    return gulp.src('source/css/main.css')
      .pipe(postcss(processors, { syntax: scss }))
      .pipe(gulp.dest('source/build/css'))
  })
  
  gulp.task('default', ['css'])
  
new_contents: const gulp = require('gulp')
  const lost = require('lost')
  const cssnano = require('cssnano')
  const mqpacker = require('css-mqpacker')
  const scss = require('postcss-scss')
  const nested = require('postcss-nested')
  const cssnext = require('postcss-cssnext')
  const atImport = require('postcss-import')
  const postcss = require('gulp-postcss')
  
  gulp.task('css', () => {
    var processors = [
      atImport,
      cssnext({ browsers: ['last 2 versions'] }),
      lost,
      nested,
      mqpacker,
      cssnano({ autoprefixer: false })
    ]
    return gulp.src('source/css/main.css')
      .pipe(postcss(processors, { syntax: scss }))
      .pipe(gulp.dest('source/build/css'))
  })
  
  gulp.task('default', ['css'])
  
subject: Fix typo