Macro std::result::try

macro try($res) { ... }

source

Extract the success value or short-circuit the calling function.

When expression is suffixed with ?, this is de-sugared to an invocation of try macro on the expression.

Expands to the following expression 

if $.is_ok() {
    $.unwrap()
} else {
    return Result::err(self.unwrap_err())
}

See also try for Option.