Function normalize_guard 

pub fn normalize_guard(guard: &str) -> &str

Normalise a guard name for comparison.

Strips language-specific prefixes that refer to the same object:

• self.mu → mu (Rust / Python)
• this->mu → mu (C++ member)
• this.mu → mu (Go/Java style)
• Leading & / * dereference operators

Only the outermost layer of each prefix is stripped so that deeply qualified names (e.g. self.inner.mu) still compare differently from self.outer.mu.