input: Write a function to merge two sorted lists A and B into a single sorted list. The function should compare the first elements of both lists and add the smaller element to the result list. This process should continue until all elements from both lists are added to the result list. If one list is exhausted, the remaining elements of the other list should be appended directly to the result list.
  def merge_sort(A, B):
   result = [] 
   i, j = 0, 0
  
   while i < len(A) and j < len(B):
   if A[i] < B[j]:
   result.append(A[i])
   i += 1
   else:
   result.append(B[j])
   j += 1
  
   result += A[i:]
   result += B[j:]
  
   return result
  
  assert merge_sort([3, 6, 8, 10, 11], [2, 5, 7, 12])==[2, 3, 5, 6, 7, 8, 10, 11, 12]
  assert merge_sort([1, 3, 5], [2, 4, 6])==[1, 2, 3, 4, 5, 6]
  assert merge_sort([], [1, 2, 3])==[1, 2, 3]
  assert merge_sort([1, 2, 3], [])==[1, 2, 3]
  assert merge_sort([], [])==[]
output: def merge_sort(A, B):
   result = [] 
   i, j = 0, 0
  
   while i < len(A) and j < len(B):
      if A[i] < B[j]:
          result.append(A[i])
          i += 1
      else:
          result.append(B[j])
          j += 1
  
   result += A[i:]
   result += B[j:]
  
   return result