How to use the chloride.crypto_auth function in chloride

var u          = require('./util')

var isBuffer = Buffer.isBuffer

//UTILS

function clone (obj) {
  var _obj = {}
  for(var k in obj) {
    if(Object.hasOwnProperty.call(obj, k))
      _obj[k] = obj[k]
  }
  return _obj
}

var hmac = sodium.crypto_auth

exports.hash = u.hash

exports.getTag = u.getTag

function isObject (o) {
  return 'object' === typeof o
}

function isFunction (f) {
  return 'function' === typeof f
}

function isString(s) {
  return 'string' === typeof s
}