Python implementation of merge sort

merge.py

class MergeSort(object):
    def __init__(self):
        pass
    
    def merge(self, left, right):
        ans = []
        while left and right:
            if left[0] < right[0]:
                ans.append(left.pop(0))                
            else:
                ans.append(right.pop(0))                

        while left:
            ans.append(left.pop(0))
        while right:
            ans.append(right.pop(0))

        return ans

        

    def msort(self, array):
        if len(array) <= 1:
            return array
        else:
            m = len(array) // 2
            
            l = self.msort(array[:m])
            r = self.msort(array[m:])
            
            return self.merge(l, r)
                
if __name__ == "__main__":
    m = MergeSort();

    print(m.msort([9, 8, 7, 6, 5, 4, 3, 2, 1]))