title: How to not override values in registry with .reg file?
body: <p>I need to save registry value only if the key is absent.
  How can I do this?</p>
  
  <p>Example:</p>
  
  <p>"key1": 1</p>
  
  <p>My reg file:</p>
  
  <p>"key1": 2
  "key2": 2</p>
  
  <p>After execution I wish to see registry 
  "key1": 1, "key2": 2</p>
  
  <p>Is it possible?</p>