example

"cities": 
[
	{
		"name" : 'NYC',
		"neighbourhoods":
		{
			"buildings":
			[
				{
				  "grade": "A",
					
				},
				{
				  "grade": "B"
				},
				{
				  "grade": "C"
				}
			]
		}
	},
	{
		"name" : 'CHICAGO',
		"neighbourhoods":
		{
			"buildings":
			[
				{
				  "grade": "D",
					
				},
				{
				  "grade": "E"
				},
				{
				  "grade": "F"
				}
			]
		}
	}
]