title: from list of dictionaries make a dict such that the same value in the dictionaries will become the key and the values are the items which are left
body: <p>In the given dictionary we have <code>label</code>, <code>parent_label</code> and <code>url</code> as the keys. Same <code>parent_label</code> should contain the <code>[label,url]</code>. If the <code>parent_label</code> is duplicated then the <code>[label, url]</code> of that particular <code>parent_label</code> should be appended. </p>
  
  <p>The input is </p>
  
  <pre><code>top = [{u'label': u'Square HSS Tool Bits',
          u'parent_label': u'Lathe Tools',
          u'url': u'/hss-tools/hss-square-tool-bits'},
          {u'label': u'HSS Tapped Punches',
          u'parent_label': u'Press Tools',
          u'url': u'/hss-tapped-punches'},
         {u'label': u'Carbide Radius End Mills',
         u'parent_label': u'Milling Tools',
         u'url': u'/carbide-radius-end-mills'},
         {u'label': u'HSS Mini Straight Punches',
         u'parent_label': u'Press Tools',
         u'url': u'/hss-mini-straight-punches'},
         {u'label': u'Carbide Square Tool Bits',
         u'parent_label': u'Lathe Tools',
         u'url': u'/carbide-square-tool-bits'},
         {u'label': u'HSS Center Drill Bits',
         u'parent_label': u'Drilling Tools',
         u'url': u'/hss-tools/hss-center-drill'},
         {u'label': u'Rectangular HSS Tool Bits',
          u'parent_label': u'Lathe Tools',
          u'url': u'/rectangular-hss-tool-bits'},
          {u'label': u'News', u'parent_label': u'About Us', u'url': 
          u'/news'}]
  </code></pre>
  
  <p>The output should look like,</p>
  
  <pre><code>{'Lathe Tools' : [[u'Square HSS Tool Bits',u'/hss-tools/hss-square- 
      tool-bits'],[u'Rectangular HSS Tool Bits',u'/rectangular-hss-tool-bits']],
  'Press Tools':[['HSS Tapped Punches',u'/hss-tapped-punches'],[u'HSS Mini Straight Punches',u'/hss-mini-straight-punches'],....]
  </code></pre>
  
  <p>I've tried like :</p>
  
  <pre><code>for i in top:
      if i['parent_label'] in k.keys():
          k[i['parent_label']] = [[i['label'],i['url']]]
  </code></pre>
  
  <p>my o/p is :</p>
  
  <pre><code> {u'About Us': [[u'News', u'/news']],
   u'Drilling Tools': [[u'HSS Center Drill Bits',
   u'/hss-tools/hss-center-drill']],
   u'Lathe Tools': [[u'Rectangular HSS Tool Bits',
    u'/rectangular-hss-tool-bits']],
   u'Milling Tools': [[u'Carbide Radius End Mills',
   u'/carbide-radius-end-mills']],
   u'Press Tools': [[u'HSS Mini Straight Punches',
    u'/hss-mini-straight-punches']]}
  </code></pre>
  
  <p>Please help me out guys. 
  Thanks </p>