What you've written is not pi, it's a procedure for computing pi. Python expressions are not a notation, they fail basic requirements for a reasonable notation (for example you cannot generally determine whether two Python expressions are equal or not).
You may find it interesting to learn that one cannot generally determine whether two real numbers are equal or not: equality on real numbers is undecidable.
I'm well aware. It's also the case that there is no good notation for the real numbers; in particular since any given notation system can only represent countably many distinct entities, almost all real numbers will be are unrepresentable in that notation system. Therefore the notion that the full set of reals actually exists is extremely dubious.
