title: Convert python dictionary lists to a tree format
body: <p>Our crawling team has captured industry information on shopping sites such as.</p>
  
  <pre><code>industry_list = [
    {
       "parent_ind" : "Clothing",
       "name" : "shirt"
    },
    {
       "name": "Clothing"
    },
    {
       "parent_ind" : "Clothing",
       "name" : "jeans"
    },
    {
       "parent_ind" : "Clothing",
       "name" : "Dress"
    },
    {
       "name": "Digital Products"
    },
    {
      "parent_ind" : "Digital Products",
       "name": "computer parts"
    },
    {
      "parent_ind" : "computer parts",
       "name": "Hard Disk"
    },
  ]
  </code></pre>
  
  <p>For ease of access, we would like to be able to convert this to a tree format, for example:</p>
  
  <pre><code>{
    "Digital Products": {
      "computer parts": {
          "Hard Disk" : {}
       }
    },
    "Clothing" : {
       "shirt": {},
      "jeans": {},
      "Dress": {}
    }
  }
  
  </code></pre>