title: Plot edges of a tree in Python
body: <p>What is an effective way to plot a list of coordinates in the form [(x1,y1),(x2,y2)], where each pair of coordinates is connected by a line (as shown below). I'd like to avoid use of non-core packages (core being pandas, matplotlib, numpy, ...)</p>
  
  <p>Example:</p>
  
  <pre><code>c = [[(0, 4), (1, 3)],
       [(0, 4), (1, 5)],
       [(1, 3), (2, 2)],
       [(1, 3), (2, 4)],
       [(1, 5), (2, 4)],
       [(1, 5), (2, 6)],
       [(2, 2), (3, 1)],
       [(2, 2), (3, 3)],
       [(2, 4), (3, 3)],
       [(2, 4), (3, 5)],
       [(2, 6), (3, 5)],
       [(2, 6), (3, 7)]]
  </code></pre>
  
  <p>to be plotted as (with labels):</p>
  
  <p><a href="https://i.stack.imgur.com/dtfyc.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dtfyc.jpg" alt="enter image description here"></a></p>