where is the lean4 core libary defined?

Stream: lean4

[Arien Malec]

I know there's std4, but the Nat directory doesn't have the core definition of Nat in the same way that the lean3 equivalent does, and despite hunting around core lean4 I haven't been able to find the lean3 equivalent....

[Julian Berman]

If you type #check Nat in a file and hit go to definition in your editor (F12 in VSCode I think) you'll get brought to the definition. It's in lean/Init/prelude.lean it seems.