diff --git a/able-script-test/parse_test.able b/able-script-test/parse_test.able
index 4848030f..4ac0e3e3 100644
--- a/able-script-test/parse_test.able
+++ b/able-script-test/parse_test.able
@@ -1 +1 @@
-a(3,)
\ No newline at end of file
+1 + 4
\ No newline at end of file
diff --git a/src/parser/item.rs b/src/parser/item.rs
index eabea924..34d0b480 100644
--- a/src/parser/item.rs
+++ b/src/parser/item.rs
@@ -35,6 +35,12 @@ pub enum Expr {
         iden: Iden,
         args: Vec<Expr>,
     },
+
+    Addition {
+        left: Box<Expr>,
+        right: Box<Expr>,
+    },
+
     Literal(Value),
     Identifier(Iden),
     Melo(Iden),
diff --git a/src/parser/ops.rs b/src/parser/ops.rs
index 0e8bb5d7..04ebde30 100644
--- a/src/parser/ops.rs
+++ b/src/parser/ops.rs
@@ -1,8 +1,7 @@
-use std::collections::HashMap;
-
 use super::*;
 
 impl<'a> Parser<'a> {
+    /// Parse operations (got identifier/value)
     pub(super) fn parse_ops(&mut self, token: Token) -> Result<Expr, Error> {
         let iden = if let Token::Identifier(i) = token {
             Iden(i)
@@ -20,9 +19,11 @@ impl<'a> Parser<'a> {
         Ok(buf[0].clone())
     }
 
+    /// Parse function call
     fn fn_call(&mut self, iden: Iden) -> Result<Expr, Error> {
         self.lexer.next();
         let mut args: Vec<Expr> = Vec::new();
+
         while let Some(token) = self.lexer.peek() {
             match token {
                 Token::Identifier(id) => {
@@ -38,9 +39,6 @@ impl<'a> Parser<'a> {
             self.require(Token::Comma)?;
         }
         self.require(Token::RightParenthesis)?;
-        Ok(Expr::FunctionCall {
-            iden,
-            args, 
-        })
+        Ok(Expr::FunctionCall { iden, args })
     }
 }
diff --git a/src/parser/utils.rs b/src/parser/utils.rs
index eddfbea7..2b83f1aa 100644
--- a/src/parser/utils.rs
+++ b/src/parser/utils.rs
@@ -30,6 +30,7 @@ impl<'a> Parser<'a> {
         }
     }
 
+    /// Require an identifier on next and return it
     pub(super) fn require_iden(&mut self) -> Result<String, Error> {
         if let Some(Token::Identifier(id)) = self.lexer.next() {
             Ok(id)
@@ -41,6 +42,7 @@ impl<'a> Parser<'a> {
         }
     }
 
+    /// Throw unexpected token error (optionally what was expected)
     pub(super) fn unexpected_token(&mut self, expected: Option<Token>) -> Error {
         let error_msg = match expected {
             Some(s) => format!(