Attempt to add parser for return function

vine/examples/break_return.vi

@@ -0,0 +1,28 @@
+
+use std::{io::println, u32};
+
+fn main(io) {
+  println("hey");
+
+
+  // let a = unit();
+  // let b = loop_unit();
+
+  println("hey");
+
+  /*
+  if a == b {
+    println("Hurray for units!")
+  }
+  */
+}
+
+fn unit() {
+  return;
+}
+
+fn loop_unit() {
+  return loop {
+    break;
+  }
+}

vine/src/parser.rs

@@ -248,10 +248,24 @@ impl<'ctx, 'src> VineParser<'ctx, 'src> {
 
   fn _parse_expr_prefix(&mut self, span: usize) -> Parse<'src, ExprKind> {
     if self.eat(Token::Return)? {
+      if self.check(Token::Semi) {
+        self.eat(Token::Semi)?;
+        return Ok(ExprKind::Return(Box::new(Expr {
+          span: self.span(),
+          kind: ExprKind::Tuple(Vec::new()),
+        })));
+      }
       return Ok(ExprKind::Return(Box::new(self.parse_expr_bp(BP::ControlFlow)?)));
     }
     if self.eat(Token::Break)? {
-      return Ok(ExprKind::Break(Box::new(self.parse_expr_bp(BP::ControlFlow)?)));
+      if self.check(Token::Semi) {
+        self.eat(Token::Semi)?;
+        return Ok(ExprKind::Return(Box::new(Expr {
+          span: self.span(),
+          kind: ExprKind::Tuple(Vec::new()),
+        })));
+      }
+      return Ok(ExprKind::Return(Box::new(self.parse_expr_bp(BP::ControlFlow)?)));
     }
     if self.eat(Token::Continue)? {
       return Ok(ExprKind::Continue);