input: Write a function to handle errors while reading data from a JSON file. If the file does not exist, print "The file specified does not exist.". If the file is not in a valid JSON format, print "The file specified is not in a valid JSON format.". If no errors occur, return the data read from the file.
  
  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('valid_data.json')=={'key': 'value'}
  assert read_data_from_json('nonexistent_file.json')=="The file specified does not exist."
  assert read_data_from_json('invalid_data.json')=="The file specified is not in a valid JSON format."
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.")