Function path_value 

pub fn path_value(
    field: &str,
    value: &str,
    pattern: &str,
) -> Result<String, Error>

value, a relative resource name, as the path segments of a request, checking it has the form pattern, such as projects/*/zones/*/volumes/*, gives it. field names it in the error. Service::path_value also takes a full resource name of its service.