Format code.

core/src/main/kotlin/org/nwapw/abacus/tree/FunctionNode.kt

@@ -36,7 +36,7 @@ data class FunctionNode(val function: String) : TreeNode() {
      *
      * @node the node to append.
      */
-    fun appendChild(node: TreeNode){
+    fun appendChild(node: TreeNode) {
         children.add(node)
     }
 
@@ -45,7 +45,7 @@ data class FunctionNode(val function: String) : TreeNode() {
      *
      * @node the node to prepend.
      */
-    fun prependChild(node: TreeNode){
+    fun prependChild(node: TreeNode) {
         children.add(0, node)
     }
 

core/src/main/kotlin/org/nwapw/abacus/tree/Reducer.kt

@@ -6,7 +6,7 @@ package org.nwapw.abacus.tree
  * The reducer walks the tree, visiting the children first, converting them into
  * a value, and then attempts to reduce the parent. Eventually, the single final value is returned.
  */
-interface Reducer <out T> {
+interface Reducer<out T> {
 
     /**
      * Reduces the given tree node, given its already reduced children.
@@ -14,6 +14,6 @@ interface Reducer <out T> {
      * @param treeNode the tree node to reduce.
      * @param children the list of children, of type T.
      */
-    fun reduceNode(treeNode: TreeNode, vararg children: Any) : T?
+    fun reduceNode(treeNode: TreeNode, vararg children: Any): T?
 
 }

core/src/main/kotlin/org/nwapw/abacus/tree/TreeNode.kt

@@ -5,6 +5,6 @@ package org.nwapw.abacus.tree
  */
 abstract class TreeNode {
 
-    abstract fun <T: Any> reduce(reducer: Reducer<T>) : T?
+    abstract fun <T : Any> reduce(reducer: Reducer<T>): T?
 
 }