title: Combining 2 dictionaries with common key
body: <p>I have two dictionaries and need to combine the values of similar keys in them. Here's an example:</p>
  
  <pre><code>dict1 = {'key1':[value11,value12,value13] , 'key2':[value21,value22,value23]}
  dict2 = {'key1':[value14,value15] , 'key2':[value24,value25]}
  </code></pre>
  
  <p>I used :</p>
  
  <pre><code>dict3 = {}
  for key in (dict1.viewkeys() | dict2.keys()):
      if key in dict1: dict3.setdefault(key, []).append(dict1[key])
      if key in dict2: dict3.setdefault(key, []).append(dict2[key])
  </code></pre>
  
  <p>which gives me:</p>
  
  <pre><code>dict3 = {'key1':[[value11,value12,value13],[value14,value15]] , 'key2':[[value21,value22,value23],[value24,value25]]}
  </code></pre>
  
  <p>What I want is a simple one like:</p>
  
  <p><strong>Desired output</strong> :  </p>
  
  <pre><code> dict3 = {'key1':[value11,value12,value13,value14,value15] , 'key2':[value21,value22,value23,value24,value25]}
  </code></pre>