title: Remove entire list elements which contain a certain string
body: <p>var1 is a list:</p>
  
  <pre><code>var1 &lt;- list(c("tall tree", "fruits", "star"),  
               c("tree tall", "pine tree", "tree pine", "black forest", "water"), 
               c("apple", "orange", "grapes"), 
               c("ancient pine tree", "all trees"))
  </code></pre>
  
  <p>I need to remove those elements entirely from the list which contains the term "pine".</p>
  
  <p>The desired answer is a list:</p>
  
  <pre><code>[[1]]
  [1] "tall tree" "fruits"    "star"    
  [[2]]
  [1] "apple"  "orange" "grapes"
  </code></pre>
  
  <p>Thanks</p>