def update_nickserv(disable, user, pass)
      @nickserv_username = valid! user, valid_string(user), :@nickserv_username,
                                  invalid_error: 'invalid NickServ username %s'
      @nickserv_password = valid! pass, valid_string(pass), :@nickserv_password,
                                  invalid_error: 'invalid NickServ password %s'
      return unless disable

      @nickserv_username = nil
      @nickserv_password = nil
    end
def update_nickserv(disable, user, pass)
      @nickserv_username = valid! user, valid_string(user), :@nickserv_username,
                                  invalid_error: 'invalid NickServ username %s'
      @nickserv_password = valid! pass, valid_string(pass), :@nickserv_password,
                                  invalid_error: 'invalid NickServ password %s'
      return unless disable

      @nickserv_username = nil
      @nickserv_password = nil
    end
Updates the NickServ authentication details of this network.

 @param disable [Boolean] whether to disable NickServ, or +nil+ to keep the
                          current value.
 @param user [String] the NickServ username, or +nil+ to keep the
                          current value
 @param pass [String] the NickServ password, or +nil+ to keep the
                          current value