How to use the chloride.crypto_box_easy function in chloride

var sodium = require('chloride')
var scalarmult = sodium.crypto_scalarmult
var box  = sodium.crypto_box_easy
var secretbox = sodium.crypto_secretbox_easy
var secretbox_open = sodium.crypto_secretbox_open_easy
var keypair = sodium.crypto_box_keypair
var concat = Buffer.concat

function randombytes(n) {
  var b = new Buffer(n)
  sodium.randombytes(b)
  return b
}

function setMax (m) {
  m = m || DEFAULT_MAX
  if (m < 1 || m > 255)
    throw new Error('max recipients must be between 0 and 255.')
  return m