'Remove a CFGNode from self.graph as well as from the function manager (if it is the beginning of a function)
:param CFGNode node: The CFGNode to remove from the graph.
:return: None'

def _remove_node(self, node):

    self.graph.remove_node(node)
    if (node.addr in self._nodes):
        del self._nodes[node.addr]
    if (node.addr in self.kb.functions):
        del self.kb.functions[node.addr]
    if (node.addr in self.kb.functions.callgraph):
        self.kb.functions.callgraph.remove_node(node.addr)
