code: function initialize (provider, configuration) {
    var serverType = configuration.serverType || provider.serverType || 'LDAP'
    var strategy
    if (serverType === 'AD') {
      strategy = new ADStrategy(
        { server: configuration, passReqToCallback: true },
        verifier(provider, configuration)
      )
    } else {
      strategy = new LdapStrategy(
        { server: configuration, passReqToCallback: true },
        verifier(provider, configuration)
      )
    }
    return strategy
  }
docs: Initialize