FOSS gamedev and creative worlds

Hello guys,
I'm new to making mods, and I want to make one for my private server that adds an extra liquid. I would like some example code to show me how it's done. I couldn't find the water lua code thats why.'

Thanks

Look at the default mod in games/minetest_game/mods/default/init.lua and copy the code of water or lava.

Thanks for the help. :)