title: Remove borders from bars in histogram in R
body: <p>How can I remove the borders around bars in R, so that only the fill remains?</p>
  <p>Instead of this:</p>
  <p><img src="https://i.stack.imgur.com/TfaMa.png" alt="enter image description here" /></p>
  <p>I want this:</p>
  <p><img src="https://i.stack.imgur.com/dlgbe.png" alt="enter image description here" /></p>
  <h1>I do <em>not</em> want to color the borders!</h1>