title: Print every 3 strings who are start from special symbols
body: <p>I have file like this:</p>
  
  <pre><code>user bbbb 
  user bbbb 
  user bbbb 
  Server sent 214221
  Server receive 134212
  user aaaa 
  Server sent 2222
  Server receive 1231231
  user cccc 
  Server sent 32424
  Server receive 3242352
  user dddd 
  Server sent 522
  Server receivce 21652532
  user eeee 
  user ffff 
  Server sent 32563
  Server receive 9045432
  user aaaa 
  Server sent 3256
  Server receive 923211
  user gggg 
  Server sent 75425
  Server receive 125463
  user dddd 
  user dddd 
  Server sent 35262
  Server receive 456438
  </code></pre>
  
  <p>I want to parse this file for extract every 3 string(first string started "user", second - "Server sent", third - "Server receive".</p>
  
  <p>I want to have result similar to this:</p>
  
  <pre><code>user bbbb 
  Server sent 214221
  Server receive 134212
  user aaaa 
  Server sent 2222
  Server receive 1231231
  user cccc 
  Server sent 32424
  Server receive 3242352
  user dddd 
  Server sent 522
  Server receivce 21652532
  user ffff 
  Server sent 32563
  Server receive 9045432
  user aaaa 
  Server sent 3256
  Server receive 923211
  user gggg 
  Server sent 75425
  Server receive 125463
  user dddd 
  Server sent 35262
  Server receive 456438
  </code></pre>
  
  <p>I want skip all repetition of string "user".
  Just need this strings:</p>
  
  <pre><code>user
  Server sent
  Server receive
  </code></pre>