Code is not modelled mathematically, it is defined mathematically.
It exists as an abstraction which is fully defined by operational semantics and denotational semantics, not modelled or approximated.
In the counter example of a quark, that exists in nature and is modelled by mathematics, but not defined by mathematics.
https://en.wikipedia.org/wiki/Formal_language
https://en.wikipedia.org/wiki/Semantics_(computer_science)
Code is not modelled mathematically, it is defined mathematically.
It exists as an abstraction which is fully defined by operational semantics and denotational semantics, not modelled or approximated.
In the counter example of a quark, that exists in nature and is modelled by mathematics, but not defined by mathematics.
https://en.wikipedia.org/wiki/Formal_language
https://en.wikipedia.org/wiki/Semantics_(computer_science)