title: What is being plotted by plt.plot with a tuple argument?
body: <p>This code snippet:</p>
  <pre><code>import matplotlib.pyplot as plt
  
  plt.plot(([1, 2, 3], [1, 2, 3]))
  plt.show()
  </code></pre>
  <p>produces:</p>
  <p><a href="https://i.stack.imgur.com/AYjQk.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/AYjQk.png" alt="enter image description here" /></a></p>
  <p>What function is being plotted here? Is this use case described in matplotlib documentation?</p>
  <hr />
  <p>This snippet:</p>
  <pre><code>plt.plot(([1, 2, 3], [1, 2, 3], [2, 3, 4]))
  </code></pre>
  <p>produces:</p>
  <p><a href="https://i.stack.imgur.com/yg61X.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yg61X.png" alt="enter image description here" /></a></p>