'Return a local transition graph that only contain nodes in current function.'

@property
def graph(self):

    if (self._local_transition_graph is not None):
        return self._local_transition_graph
    g = networkx.DiGraph()
    if (self.startpoint is not None):
        g.add_node(self.startpoint)
    for block in self._local_blocks.itervalues():
        g.add_node(block)
    for (src, dst, data) in self.transition_graph.edges_iter(data=True):
        if ('type' in data):
            if ((data['type'] == 'transition') and (('outside' not in data) or (data['outside'] is False))):
                g.add_edge(src, dst, attr_dict=data)
            elif ((data['type'] == 'fake_return') and ('confirmed' in data) and (('outside' not in data) or (data['outside'] is False))):
                g.add_edge(src, dst, attr_dict=data)
    self._local_transition_graph = g
    return g
