span> <span class='st'>"arc_layer"</span>
  , <span class='kw'>origin</span> <span class='kw'>=</span> <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span>(<span class='st'>"start_lon"</span>, <span class='st'>"start_lat"</span>)
  , <span class='kw'>destination</span> <span class='kw'>=</span> <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span>(<span class='st'>"end_lon"</span>, <span class='st'>"end_lat"</span>)
  , <span class='kw'>stroke_from</span> <span class='kw'>=<