Prefix a key with a sublevel prefix
npm install sublevel-prefixer
var prefixer = require('sublevel-prefixer')
var prefix = prefixer('!') // use '!' as the separator
// using string keys
console.log(prefix('my-prefix', 'my-key')) // !my-prefix!my-key
// using binary keys
console.log(prefix('my-prefix', new Buffer('my-key'))) // returns above as a bufferMIT