def move_edge_source(self, edge_id, node_a, node_b):
<EOL>edge = self.get_edge(edge_id)<EOL>edge['<STR_LIT>'] = (node_b, edge['<STR_LIT>'][<NUM_LIT:1>])<EOL>node = self.get_node(node_a)<EOL>node['<STR_LIT>'].remove(edge_id)<EOL>node = self.get_node(node_b)<EOL>node['<STR_LIT>'].append(edge_id)<EOL>
Moves an edge originating from node_a so that it originates from node_b.