                 {
                        name: 'b1'
                    },
                    {
                        name: 'c'
                    }
                    ],
                    links: [
                    {
                        source: 'a',
                        target: 'a1',
                        value: 5
                    },
                    {
                        source: 'a',
                        target: 'a2',
                        value: 3
                    },