Do not export fn_native.

src/lib.rs

@@ -76,7 +76,7 @@ mod engine;
 mod error;
 mod fn_call;
 mod fn_func;
-pub mod fn_native;
+mod fn_native;
 mod fn_register;
 mod module;
 mod optimize;
@@ -92,6 +92,7 @@ mod utils;
 pub use any::Dynamic;
 pub use engine::Engine;
 pub use error::{ParseError, ParseErrorType};
+pub use fn_native::IteratorFn;
 pub use fn_register::{RegisterFn, RegisterResultFn};
 pub use module::Module;
 pub use parser::{ImmutableString, AST, INT};