Top K Frequent elements

class Solution:
    def top_frequent_elements(self, array, k_elements):
        frequency = {}
        for num in array:
            if num not in frequency:
                frequency[num] = 1
            else:
                frequency[num] += 1

        return_value = []

        for k in range(k_elements):
            max_count = 1
            most_frequent_num = next(iter(frequency))
            for key,value in frequency.items():
                if value > max_count:
                    max_count = value
                    most_frequent_num = key
            return_value.append(most_frequent_num)
            del(frequency[most_frequent_num])

        return return_value


print("Hello World!")
sample1 = [2,1,1,3,1,2]
k1 = 2
sol = Solution()
result1 = sol.top_frequent_elements(sample1, k1)
print(result1)
assert(result1 == [1,2])


sample2 = [1]
k2 = 1
sol = Solution()
result2 = sol.top_frequent_elements(sample2, k2)
print(result2)
assert(result2 == [1])


print("Good bye cruel World")