Can't install gulp?

Question

npm

Hello! Can't install gulp... here are my steps:

npm i gulp -g
npm init (В папке проекта)
npm i gulp --save-dev(в папке проекта)

I create a file - gulpfile.js
I write in it:
var gulp = require('gulp');
And also a test task:

gulp.task('mytask', function(){
         console.log('Hello');
    });

Well, after running the task - gulp task
Displays a message - "gulp" is not an internal or external
command, executable program or batch file.
Node.js - 8.2.0