text: const leettree = require('leettree')
  const maxLevelSum = require('./solution')
  
  test('Example 1', () => {
    const array = [1, 7, 0, 7, -8, null, null]
    const root = leettree.deserialize(array)
  
    const result = maxLevelSum(root)
  
    expect(result).toBe(2)
  })
  