Flatten a nested object containing arrays using dot notation

Given a nested object that may contain both objects and arrays, flatten it into a single-level object.

• Use dot notation to represent nested keys
• For arrays, use the index as the key
• The structure depth can be arbitrary

Input:
{

a: { b: 6, d: { k: 90 } },

x: [9, { m: 0 }]

}

Expected Output :

{

"a.b": 6,

"a.d.k": 90,

"x.0": 9,

"x.1.m": 0

}