title: Save lines of txt file into csv
body: <p>I have a txt file that looks like this</p>
  <pre><code>a,b,c
  0,0,0
  0,0,0
  *
  x,y,z
  1,1,1
  1,1,1
  *
  u,v,w
  9,9,9
  9,9,9
  *
  </code></pre>
  <p>I would like to save every three lines excluding the asterisk into csv files so my csv files look like this.</p>
  <p>0.csv</p>
  <pre><code>a,b,c
  0,0,0
  0,0,0
  </code></pre>
  <p>1.csv</p>
  <pre><code>x,y,z
  1,1,1
  1,1,1
  </code></pre>
  <p>2.csv</p>
  <pre><code>u,v,w
  9,9,9
  9,9,9
  </code></pre>
  <p>Is there any efficient way to do this? Thank you so much.</p>