input: Write a function to modify the following Python code to handle errors in reading a JSON file. If the file specified does not exist, print "The file specified does not exist." If the file specified is not in a valid JSON format, print "The file specified is not in a valid JSON format."
  def read_data_from_json(filename):
      try:
          with open(filename, 'r') as f:
              data = json.load(f)
          return data
      except FileNotFoundError:
          print("The file specified does not exist.")
      except json.decoder.JSONDecodeError:
          print("The file specified is not in a valid JSON format.")
  assert read_data_from_json("existing.json") == {"key": "value"}
  assert read_data_from_json("nonexistent.json") == None
  assert read_data_from_json("invalid.json") == None
output: def read_data_from_json(filename):
      try:
          with open(filename, 'r') as f:
              data = json.load(f)
          return data
      except FileNotFoundError:
          print("The file specified does not exist.")
      except json.decoder.JSONDecodeError:
          print("The file specified is not in a valid JSON format.")