Function mask 

pub fn mask(_valor: &str) -> &'static str

Masks a sensitive value without leaking useful characters.

Always returns the static placeholder FIXED_MASK. No heap allocation.

Examples

use ssh_cli::masking::mask;

assert_eq!(mask("curto"), "***");
assert_eq!(mask("password-secreta-muito-longa-aqui-123456"), "***");
assert_eq!(mask("a"), ssh_cli::masking::FIXED_MASK);