did some more clarifying of graph task

developer/concurrent-tree.ipynb

@@ -38,7 +38,7 @@
    "source": [
     "Write Python code that finds a minimum spanning tree of an undirected graph using concurrent methods. State any additional assumptions you have made. Prepare to offer some context regarding spanning trees during an interview. If you are familiar with an external library that offers high-level constructs to program concurrently, then feel free to use it. We consider it a bonus if your choices are such that your solution can be modified to run on a cluster, but this is by no means a requirement.\n",
     "\n",
-    "As an optional extra, try to write Python code that finds a minimum-cost spanning tree using concurrent methods. What known algorithm(s) did you use or modify to create your solution? Prepare to justify your choice(s) during an interview."
+    "As an optional extra, try to write Python code that finds a minimum-cost spanning tree (of an undirected graph) using concurrent methods. What known algorithm(s) did you use or modify to create your solution? Prepare to justify your choice(s) during an interview."
    ]
   },
   {