title: matplotlib 2d line line,=plot comma meaning
body: <p>I'm walking through basic tutorials for matplotlib, and the example code that I'm working on is:</p>
  <pre class="lang-py prettyprint-override"><code>import numpy as np
  
  import matplotlib.pylab as plt
  
  x=[1,2,3,4]
  y=[5,6,7,8]
  
  line, = plt.plot(x,y,'-')
  
  plt.show()
  </code></pre>
  <p>Does anyone know what the comma after line (<code>line,=plt.plot(x,y,'-')</code>) means?
  I thought it was a typo but obviously the whole code doesn't work if I omit the comma.</p>