title: depth-first graph search that returns path to goal
body: <p>I've been trying this all week and cannot, for the life of me, figure it out.</p>
  
  <p>I know that I need to have a helper function that will recurse and return pathSoFar. I can't seem to get my head around the recursion.</p>
  
  <p>I'm so confused that I can't even formulate exactly what the problem is besides recursion.</p>
  
  <p>Thanks for any help.</p>
  
  <p>EDIT: OK, I'll clarify a little bit. One thing that confuses me is what path is returned when a node has no neighbors. The goal path may be returned first, but then, because the helper is still recursing, it can return a dead-end path. I guess I'm confused about backtracking.</p>