Arity for builtins (#28)

Old-style function call

Utility for running opa yaml tests

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/lib.rs

@@ -7,6 +7,7 @@ pub mod interpreter;
 pub mod lexer;
 pub mod parser;
 pub mod scheduler;
+mod utils;
 pub mod value;
 
 pub use ast::*;