Given a list of strings, group the strings that are anagrams of each other. Return the grouped anagrams as a list of lists. Each group should contain strings that are anagrams, and the order of groups and order of strings inside each group does not matter.
['eat', 'tea', 'tan', 'ate', 'nat', 'bat'][['eat', 'tea', 'ate'], ['tan', 'nat'], ['bat']]