Parser tweak

src/board/tree.rs

@@ -93,7 +93,8 @@ impl TreeElement {
 	pub fn evaluate(&self) -> Option<f32> {
 		match self {
 			Self::Number(x) => Some(*x),
-			Self::Partial(_) => None,
+			// Try to parse strings of a partial
+			Self::Partial(s) => s.parse().ok(),
 			Self::Add { l, r } => {
 				let l = l.evaluate();
 				let r = r.evaluate();