input: Write a function to calculate the mean and range (highest - lowest) of a given data set.
  assert mean_and_range([2, 3, 6, 12, 21, 41])==(14.166666666666666, 39)
  assert mean_and_range([10, 20, 30, 40, 50])==(30.0, 40)
  assert mean_and_range([1, 1, 1, 1, 1])==(1.0, 0)
output: def mean_and_range(data):
      mean = sum(data) / len(data)
      range_val = max(data) - min(data)
      return mean, range_val