Write a method to sort an array of strings so that all the anagrams are in the same group.
Note: This problem is slightly different from the original one the book.
Example:
Input: ["eat", "tea", "tan", "ate", "nat", "bat"],
Output:
[
["ate","eat","tea"],
["nat","tan"],
["bat"]
]
Notes:
- All inputs will be in lowercase.
- The order of your output does not matter.