title: Verify if 2 LineString (shapely) are parallel
body: <p>I have 2 <code>shapely.LineString</code>, and I would like to verify if they are parallel.</p>
  
  <pre><code>a = LineString(((0, 0), (0  , 1)))
  b = LineString(((1, 0), (0.9, 1))) #Not intersecting, but also not parallel)
  </code></pre>
  
  <p>When I use intersects, the <code>intersects</code>, it returns <code>False</code> because the 2 lines are not intersecting, but they are also not parallel.</p>
  
  <p>Is there a method in Shapely to verify parallelism? I could use the angle (via <code>np.arctan</code>).</p>