code: def move_edge_target(self, edge_id, node_a):
          
          # Grab the edge
          edge = self.get_edge(edge_id)
  
          # Remove the edge from the original "target node"
          original_target_node_id = edge['vertices'][1]
          original_target_node = self.get_node(original_target_node_id)
          original_target_node['edges'].remove(edge_id)
  
          # Add the edge to the new target node
          new_target_node_id = node_a
          new_target_node = self.get_node(new_target_node_id)
          new_target_node['edges'].append(edge_id)
  
          # Alter the vertices on the edge
          edge['vertices'] = (edge['vertices'][0], node_a)
docs: Moves an edge so that it targets node_a.