title: How does Python mimic the behavior of Perl multi-level hash chain extraction and concatenation
body: <p>I've always use Perl hash reference tricks to deal with tree structures.<br>
  This time, I have to do it in Python that I am not really familiar with.<br>
  For example, in the following code. I create a hash chain and cut it to half. Then I concatenate one piece to another hash chain.</p>
  
  <pre><code>my $hashRoot-&gt;{'1'}-&gt;{'2'}-&gt;{'C'}-&gt;{'D'} = 'val';
  my $subHash = $hashRoot-&gt;{'1'}-&gt;{'2'};             #Extract the Last 2 Level of Chain
  my $anotherHashRoot-&gt;{'A'}-&gt;{'B'} = $subHash;      #Concatenate to another Hash Chain
  
  say '$hashRoot';
  say Dump $hashRoot;
  say '$subHash';
  say Dump $subHash;
  say '$anotherHashRoot';
  say Dump $anotherHashRoot;
  </code></pre>
  
  <p>Above code generates output as following:</p>
  
  <pre><code>$hashRoot
  ---
  1:
    2:
      C:
        D: val
  
  $subHash
  ---
  C:
    D: val
  
  $anotherHashRoot
  ---
  A:
    B:
      C:
        D: val
  </code></pre>
  
  <p>In short, I am searching a Pythonic way to cut/insert/copy a hash(dict) chain as in Perl (or in C). Does anyone have the answer?</p>