title: Merging multiple dictionaries in python
body: <p>I've few dictionaries as follows:</p>
  
  <pre><code>{"item1": {"item2": "300"}}
  {"item1": {"item3": {"item4": "400"}}}
  {"item1": {"item3": {"item6": "16"}}}
  {"item1": {"item7": "aaa"}}
  {"item1": {"item8": "bbb"}}
  {"item1": {"item9": {"item10" : "2.2"}}}
  {"item1": {"item9": {"item11" : "xxx"}}}
  </code></pre>
  
  <p>I want to merge these dictionaries as follows</p>
  
  <pre><code>{
    "item1": {
      "item2": "300",
      "item3": {
        "item4": "400",
        "item6": "16"
       },
      "item7": "aaa",
      "item8": "bbb",
      "item9": {
        "item10": "2.2",
        "item11": "xxx"
       }
    }
  }
  </code></pre>
  
  <p>item1 is the first key in all dictionaries whereas the nested keys will vary. If there is same nested dictionary within a dictionary in two dictionaries the keys has to be merged (eg: item3 in dictionary 1 and 2). How can i achieve this?</p>