Parse function params

examples/test.lua

@@ -1,4 +1,4 @@
-function max ()
+function max (a, b)
     local m = a
     -- if b > a then
     --    m = b

src/ast.rs

@@ -142,7 +142,15 @@ impl Parse for Function {
         let name = stream.parse::<Node<String>>().ok();
         stream.expect(Token::Symbol('('))?;
 
-        let params = Vec::new();
+        let mut params = Vec::new();
+
+        if let Ok(param) = stream.parse() {
+            params.push(param);
+            while stream.peek() == Some(Token::Symbol(',')) {
+                stream.next();
+                params.push(stream.parse()?);
+            }
+        }
 
         stream.expect(Token::Symbol(')'))?;