***************************************************************************
@method _init
@description _init description
@returns {xxx} -- xxx
function() {
    _o('./Acl').prototype._init.call(this)

    // add a group definition called __owner__ which is a function that
    // checks to see if user._id is the same as the object owner
    var self = this
    self.groupDefinitions = self.groupDefinitions || {}
    self.groupDefinitions[self.OWNER_SPEC] = function(user) {
      return self.isOwner(user, self.object)
    }
  }