fix: if nodes has string, close #68

Author: Scrum

lib/index.js

@@ -161,7 +161,7 @@ function walk (opts, nodes) {
   let skip
 
   // loop through each node in the tree
-  return nodes.reduce((m, node, i) => {
+  return [].concat(nodes).reduce((m, node, i) => {
     // if we're skipping this node, return immediately
     if (skip) { skip--; return m }