Macro ruby_parser::use_parser

macro_rules! use_parser {
    ($func:ident) => { ... };
    ($func:ident, $output:ident) => { ... };
    ($func:ident, $output:ident, $input_type:ty, $err_type:ty) => { ... };
}

Defines the functions used by the assert_ok!, assert_partial!, and assert_err! macros