input: Write a function to output the Fibonacci sequence as a list of integers up to n terms. If n is 0, return an empty list.
  assert fibonacci_sequence(0) == []
  assert fibonacci_sequence(1) == [0]
  assert fibonacci_sequence(5) == [0, 1, 1, 2, 3]
  assert fibonacci_sequence(10) == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
  assert fibonacci_sequence(15) == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377]
output: def fibonacci_sequence(n):
      if n == 0:
          return []
      elif n == 1:
          return [0]
      sequence = [0, 1]
      for i in range(2, n):
          sequence.append(sequence[-1] + sequence[-2])
      return sequence