title: Merge Dictionaries With Values As Arrays in Swift4
body: <p>I have three dictionaries, and I want to merge these. Please Help!</p>
  
  <p>Dictionary 1:</p>
  
  <pre><code>"Abc": {
      "Def": {
          "Jkl": "xxx",
      }
  }
  </code></pre>
  
  <p>Dictionary 2:</p>
  
  <pre><code>"Abc": {
      "Ghi": {
          "Mno": "yyy",
      }
  }
  </code></pre>
  
  <p>Dictionary 3:</p>
  
  <pre><code>"Abc": {
      "Ghi": {
          "Pqr": "zzz"
      }
  }
  </code></pre>
  
  <p>I want the resulting dictionary to group similar values together and it should look like this:</p>
  
  <pre><code>"Abc": {
      "Def: {
          "Jkl": "xxx"
      },
      "Ghi": {
          "Mno": "yyy",
          "Pqr": "zzz"
      }
  }
  </code></pre>