input: Write a function to print the Fibonacci sequence up to a given number using recursion.
  assert fibonacci_sequence(5) == [0, 1, 1, 2, 3, 5]
  assert fibonacci_sequence(7) == [0, 1, 1, 2, 3, 5, 8, 13]
  assert fibonacci_sequence(10) == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
output: def fibonacci_sequence(n, a=0, b=1, sequence=None):
      if sequence is None:
          sequence = [a]
      if n == 0:
          return sequence
      sequence.append(b)
      return fibonacci_sequence(n-1, b, a+b, sequence)