old_contents: """
  TESTS is a dict with all you tests.
  Keys for this will be categories' names.
  Each test is dict with
      "input" -- input data for user function
      "answer" -- your right answer
      "explanation" -- not necessary key, it's using for additional info in animation.
  """
  
  
  TESTS = {
      "Basics": [
          {
              "input": [2, 3],
              "answer": 5,
              "explanation": "2+3=?"
          },
          {
              "input": [2, 7],
              "answer": 9,
              "explanation": "2+7=?"
          }
      ],
      "Additional": [
          {
              "input": [6, 3],
              "answer": 9,
              "explanation": "6+3=?"
          },
          {
              "input": [6, 7],
              "answer": 13,
              "explanation": "6+7=?"
          }
      ]
  }
  
new_contents: """
  TESTS is a dict with all you tests.
  Keys for this will be categories' names.
  Each test is dict with
      "input" -- input data for user function
      "answer" -- your right answer
      "explanation" -- not necessary key, it's using for additional info in animation.
  """
  
  
  TESTS = {
      "Basics": [
          {
              "input": [2, 3],
              "answer": 5,
              "explanation": "2+3=?"
          },
          {
              "input": [2, 7],
              "answer": 9,
              "explanation": "2+7=?"
          }
      ],
      "Extra": [
          {
              "input": [6, 3],
              "answer": 9,
              "explanation": "6+3=?"
          },
          {
              "input": [6, 7],
              "answer": 13,
              "explanation": "6+7=?"
          }
      ]
  }
  
subject: Test category example rename for ordering