Parse re-assignment

examples/test.lua

@@ -1,7 +1,7 @@
 function max (a, b)
     local m = a
     if a then
-       local m = b
+       m = b
     end
     return m
 end

src/ast.rs

@@ -229,6 +229,12 @@ impl Parse for Statement {
                 name,
                 expr,
             ))
+        } else if let Some(Token::Word(_)) = peeked
+            && stream.peek2() == Some(Token::Symbol('='))
+        {
+            let name = stream.parse()?;
+            stream.expect(Token::Symbol('='))?;
+            Ok(Self::Assignment(None, name, stream.parse()?))
         } else {
             Err(stream.expecting_err("statement"))
         }