input: Write a python function to remove duplicate strings from a list of lists and return a sorted list.
  assert removeduplicates([['b', 'a', 'd'], ['c', 'a', 'd'], ['a', 'f', 'g']]) == ['a', 'b', 'c', 'd', 'f', 'g']
  assert removeduplicates([['apple', 'banana'], ['banana', 'cherry'], ['apple', 'date']]) == ['apple', 'banana', 'cherry', 'date']
  assert removeduplicates([['x', 'y', 'z'], ['y', 'z'], ['x']]) == ['x', 'y', 'z']
output: def removeduplicates(list_of_lists):
      unique_strings = set()
      for sublist in list_of_lists:
          unique_strings.update(sublist)
      return sorted(unique_strings)