'Add edge between nodes, or add node if entry point
:param CFGNode cfg_node: node which is jumped to
:param CFGNode src_node: node which is jumped from none if entry point
:param str src_jumpkind: what type of jump the edge takes
:param int or str src_stmt_idx: source statements ID
:return: None'

def _graph_add_edge(self, cfg_node, src_node, src_jumpkind, src_ins_addr, src_stmt_idx):

    if (src_node is None):
        self.graph.add_node(cfg_node)
    else:
        self.graph.add_edge(src_node, cfg_node, jumpkind=src_jumpkind, ins_addr=src_ins_addr, stmt_idx=src_stmt_idx)
