'Get the corresponding exit statement ID for control flow to reach destination block from source block. The exit
statement ID was put on the edge when creating the CFG.
Note that there must be a direct edge between the two blocks, otherwise an exception will be raised.
:return: The exit statement ID'

def get_exit_stmt_idx(self, src_block, dst_block):

    if (not self.graph.has_edge(src_block, dst_block)):
        raise AngrCFGError(('Edge    (%s,    %s)    does    not    exist    in    CFG' % (src_block, dst_block)))
    return self.graph[src_block][dst_block]['stmt_idx']
