Rust - Lifetimes - Rules

Lifetimes have three shortcut rules to make it easier for developers:

1. Each parameter that is a reference gets its own lifetime
• fn foo<'a, 'b>(x: &'a str, y: &'b str)
2. If there is exactly one input lifetime parameter, that lifetime is applied to all output lifetime parameters
• fn foo<'a>(x: &'a str) -> &'a str
3. If an input lifetime parameter is &self or &mut self, the lifetime of self is automatically to all output lifetime parameters