diff --git a/nac3core/src/typecheck/expression_inference.rs b/nac3core/src/typecheck/expression_inference.rs
index 4f3ee814..3e90eb96 100644
--- a/nac3core/src/typecheck/expression_inference.rs
+++ b/nac3core/src/typecheck/expression_inference.rs
@@ -659,6 +659,9 @@ pub mod test {
     #[test_case("1 if True else False")]
     #[test_case("1 and 2")]
     #[test_case("False or 1")]
+    #[test_case("1 + False")]
+    #[test_case("1 < 2 > False")]
+    #[test_case("not 2")]
     fn test_err_msg(prog: &'static str) {
         let mut inf = new_ctx();
         let ast = rustpython_parser::parser::parse_expression(prog).unwrap();
diff --git a/nac3core/src/typecheck/symbol_resolver.rs b/nac3core/src/typecheck/symbol_resolver.rs
index a5328491..c96e75d5 100644
--- a/nac3core/src/typecheck/symbol_resolver.rs
+++ b/nac3core/src/typecheck/symbol_resolver.rs
@@ -1,6 +1,11 @@
 use super::typedef::Type;
 use super::location::Location;
-use rustpython_parser::ast::Expr;
+
+pub enum SymbolType {
+    TypeName(Type),
+    Identifier(Type),
+}
+
 pub enum SymbolValue<'a> {
     I32(i32),
     I64(i64),
@@ -9,10 +14,10 @@ pub enum SymbolValue<'a> {
     Tuple(&'a [SymbolValue<'a>]),
     Bytes(&'a [u8]),
 }
+
 pub trait SymbolResolver {
-    fn get_symbol_type(&mut self, str: &str) -> Option<Type>;
-    fn parse_type_name(&mut self, expr: &Expr<()>) -> Option<Type>;
-    fn get_symbol_value(&mut self, str: &str) -> Option<SymbolValue>;
-    fn get_symbol_location(&mut self, str: &str) -> Option<Location>;
+    fn get_symbol_type(&self, str: &str) -> Option<SymbolType>;
+    fn get_symbol_value(&self, str: &str) -> Option<SymbolValue>;
+    fn get_symbol_location(&self, str: &str) -> Option<Location>;
     // handle function call etc.
 }
\ No newline at end of file