title: Remove empty elements from list with character(0)
body: <p>How can I remove empty elements from a list that contain zero length pairlist as
  <code>character(0)</code>, <code>integer(0)</code> etc...</p>
  
  <pre><code>list2
  # $`hsa:7476`
  # [1] "1","2","3"
  # 
  # $`hsa:656`
  # character(0)
  #
  # $`hsa:7475`
  # character(0)
  #
  # $`hsa:7472`
  # character(0)
  </code></pre>
  
  <p>I don't know how to deal with them. I mean if <code>NULL</code> it is much simpler. How can I remove these elements such that just <code>hsa:7476</code> remains in the list.</p>