title: Replacing consecutively empty values in a CSV file
body: <p>I have a line of text like:</p>
  
  <pre><code>value,value,,,value,value
  </code></pre>
  
  <p>I want the two empty values to be replaced with a different value. Something like:</p>
  
  <pre><code>value,value,hello,hello,value,value
  </code></pre>
  
  <p>I'm currently trying something like:</p>
  
  <pre><code>sed -e 's/^,/hello,/' -e 's/,$/,hello/' -e 's/,,/,hello,/g'
  </code></pre>
  
  <p>That catches blank values at the beginning, end and the middle. BUT, it doesn't catch two consecutive blank values in a row. How can I update the regular expression patterns so that an indefinite number of consecutive blank values can appear in the middle?</p>