diff --git a/src/formula/mod.rs b/src/formula/mod.rs
index bd2281c..b0d4024 100644
--- a/src/formula/mod.rs
+++ b/src/formula/mod.rs
@@ -3,7 +3,7 @@ use crate::formula::node::Node;
 pub mod node;
 
 pub struct Formula {
-    root: node::Node<F>,
+    root: node::Node,
 }
 
 impl Formula {
diff --git a/src/formula/node/function.rs b/src/formula/node/function.rs
deleted file mode 100644
index f8ba181..0000000
--- a/src/formula/node/function.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-pub trait Function {
-    fn map(x: f64) -> f64;
-}
diff --git a/src/formula/node/mod.rs b/src/formula/node/mod.rs
index 6e53a7a..ea7f1d2 100644
--- a/src/formula/node/mod.rs
+++ b/src/formula/node/mod.rs
@@ -1,6 +1,5 @@
 use crate::formula::node::graph_constructor::GraphBuilder;
 
-mod function;
 mod graph_constructor;
 
 pub struct Node {
@@ -20,8 +19,13 @@ impl Node {
     }
     pub fn get_value(&self) -> f64 {
         if self.children.len() == 0 {
-            0f64
+            return (self.function)(vec![0f64]);
         }
-        for node in self.children {}
+        let mut inputs: Vec<f64> = vec![];
+        for node in &self.children {
+            inputs.push(node.get_value());
+        }
+
+        return (self.function)(inputs);
     }
 }