Function expr_ends_with_dot 

fn expr_ends_with_dot(expr: &Expr) -> bool

Returns true if the printed representation of this expression ends with a . character — specifically, an unsuffixed float literal like 0. or 45.. This is used to insert whitespace before range operators (.., ..=) so that the dots don’t merge (e.g. 0. ..45. instead of 0...45.).