title: How to append a text to file succinctly
body: <p>Instead of writing</p>
  
  <pre><code>File.open("foo.txt", "w"){|f| f.write("foo")}
  </code></pre>
  
  <p>We can write it </p>
  
  <pre><code>File.write("foo.txt", "foo")
  </code></pre>
  
  <p>Is there simpler way to write this one?</p>
  
  <pre><code>File.open("foo.txt", "a"){|f| f.write("foo")}
  </code></pre>