def tag_users(conn, %{"nicknames" => nicknames, "tags" => tags}) do
with {:ok, _} <- User.tag(nicknames, tags),
do: json_response(conn, :no_content, "")
end
def untag_users(conn, %{"nicknames" => nicknames, "tags" => tags}) do
with {:ok, _} <- User.untag(nicknames, tags),
do: json_response(conn, :no_content, "")
end