Given three groups of numbers, return a list containing all numbers that appear in more than one group (in ascending order).
number_groups([7, 8, 7, 3, 4], [2, 9, 1, 2, 1], [5, 6, 6, 6, 5]) ➞ []
number_groups([3, 8, 8, 1, 1], [9, 1, 1, 9, 9], [10, 7, 6, 6, 3]) ➞ [1, 3]
number_groups([4, 10, 9, 2, 2], [5, 3, 7, 3, 8], [6, 2, 9, 4, 2]) ➞ [2, 4, 9]
number_groups([7, 8, 4, 8, 7], [8, 5, 9, 2, 9], [6, 1, 5, 5, 6]) ➞ [5, 8]
N/A