<NME> gulpfile.js
<BEF> 'use strict';

var gulp = require( 'gulp' );
var download = require( 'gulp-download' );
var decompress = require( 'gulp-decompress' );
var convertEncoding = require( 'gulp-convert-encoding' );
var chmod = require( 'gulp-chmod' );
var postal2json = require( './lib/postal2json.js' );
var jigyosyo2json = require( './lib/jigyosyo2json.js' );
var v1 = require( './lib/v1.js' );

/**
 * Download and Decompress and Convert Encoding.
 */
function getZipCodeCSV( urls ) {
  return download( urls )
  .pipe( decompress() )
  .pipe( convertEncoding( { from: "shift_jis", to: "utf-8" } ) )
}

gulp.task( 'download', function () {
  return getZipCodeCSV( [
    'http://www.post.japanpost.jp/zipcode/dl/roman/ken_all_rome.zip',
    'http://www.post.japanpost.jp/zipcode/dl/jigyosyo/zip/jigyosyo.zip'
  ] )
  .pipe( chmod( 644 ) )
  .pipe( gulp.dest( 'api' ) );
} );

gulp.task( 'v1', function () {
  return getZipCodeCSV( [ 'http://www.post.japanpost.jp/zipcode/dl/roman/ken_all_rome.zip' ] )
  .pipe( postal2json() )
  .pipe( v1() )
  .pipe( chmod( 644 ) )
  .pipe( gulp.dest( 'api/v1' ) );
} );

gulp.task( 'v1-jigyosyo', function () {
  return getZipCodeCSV( [ 'http://www.post.japanpost.jp/zipcode/dl/jigyosyo/zip/jigyosyo.zip' ] )
  .pipe( jigyosyo2json() )
  .pipe( v1() )
  .pipe( chmod( 644 ) )
  .pipe( gulp.dest( 'api/v1' ) );
} );

gulp.task( 'default', [ 'v1', 'v1-jigyosyo' ] );
    .pipe( v1() )
    .pipe( chmod( 644 ) )
    .pipe( gulp.dest( 'api/v1' ) );
} );

gulp.task( 'default', [ 'v1', 'v1-jigyosyo' ] );

<MSG> more readable

<DFF> @@ -10,37 +10,31 @@ var jigyosyo2json = require( './lib/jigyosyo2json.js' );
 var v1 = require( './lib/v1.js' );
 
 /**
- * Download and Decompress and Convert Encoding.
+ * Create an API of the postal code.
  */
-function getZipCodeCSV( urls ) {
-  return download( urls )
-  .pipe( decompress() )
-  .pipe( convertEncoding( { from: "shift_jis", to: "utf-8" } ) )
-}
-
-gulp.task( 'download', function () {
-  return getZipCodeCSV( [
-    'http://www.post.japanpost.jp/zipcode/dl/roman/ken_all_rome.zip',
-    'http://www.post.japanpost.jp/zipcode/dl/jigyosyo/zip/jigyosyo.zip'
-  ] )
-  .pipe( chmod( 644 ) )
-  .pipe( gulp.dest( 'api' ) );
-} );
-
 gulp.task( 'v1', function () {
-  return getZipCodeCSV( [ 'http://www.post.japanpost.jp/zipcode/dl/roman/ken_all_rome.zip' ] )
-  .pipe( postal2json() )
-  .pipe( v1() )
-  .pipe( chmod( 644 ) )
-  .pipe( gulp.dest( 'api/v1' ) );
+  var urls = [ 'http://www.post.japanpost.jp/zipcode/dl/roman/ken_all_rome.zip' ];
+  return download( urls )
+    .pipe( decompress() )
+    .pipe( convertEncoding( { from: "shift_jis", to: "utf-8" } ) )
+    .pipe( postal2json() )
+    .pipe( v1() )
+    .pipe( chmod( 644 ) )
+    .pipe( gulp.dest( 'api/v1' ) );
 } );
 
+/**
+ * Create an API of the Jigyosyo postal code.
+ */
 gulp.task( 'v1-jigyosyo', function () {
-  return getZipCodeCSV( [ 'http://www.post.japanpost.jp/zipcode/dl/jigyosyo/zip/jigyosyo.zip' ] )
-  .pipe( jigyosyo2json() )
-  .pipe( v1() )
-  .pipe( chmod( 644 ) )
-  .pipe( gulp.dest( 'api/v1' ) );
+  var urls = [ 'http://www.post.japanpost.jp/zipcode/dl/jigyosyo/zip/jigyosyo.zip' ];
+  return download( urls )
+    .pipe( decompress() )
+    .pipe( convertEncoding( { from: "shift_jis", to: "utf-8" } ) )
+    .pipe( jigyosyo2json() )
+    .pipe( v1() )
+    .pipe( chmod( 644 ) )
+    .pipe( gulp.dest( 'api/v1' ) );
 } );
 
 gulp.task( 'default', [ 'v1', 'v1-jigyosyo' ] );

more readable