# Type Theory Reference

This page defines helper functions for working with natural numbers. The code blocks below use span elements with generated anchor IDs that happen to match partial selector patterns like "next-".

`def h1 (x : Nat) : Nat :=`

The function h1 takes a natural number and returns a natural number. Below is a second definition that should also be preserved.

`def h2 (x : Nat) : Nat :=`

Both h1 and h2 should appear in the output. If partial selector removal strips the span elements inside code, the function names will be missing.