Given an array of strings strs, group the anagrams together. You can return the answer in any order.

An anagram is a word formed by rearranging the letters of another word, using all the original letters exactly once.

Example:

Input: strs = ["eat","tea","tan","ate","nat","bat"]
Output: [["ate","eat","tea"],["bat"],["nat","tan"]]

Input: strs = [""]
Output: [[""]]

Input: strs = ["a"]
Output: [["a"]]