pub unsafe fn key(&mut self, builder: LLVMBuilderRef, value: LLVMValueRef) -> LLVMValueRef {
        LLVMBuildStructGEP(builder, value, KEY_INDEX, c_str!("slot.key"))
    }
Return the key pointer for the provided slot.

The slot should be a pointer.
weld/src/codegen/llvm2/dict.rs