input: Write a python function to return a list of Fibonacci sequence up to 'n' terms.
  assert fibonacci_sequence(6) == [0, 1, 1, 2, 3, 5]
  assert fibonacci_sequence(1) == [0]
  assert fibonacci_sequence(0) == []
  assert fibonacci_sequence(10) == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
output: def fibonacci_sequence(n):
      if n == 0:
          return []
      elif n == 1:
          return [0]
      sequence = [0, 1]
      while len(sequence) < n:
          sequence.append(sequence[-1] + sequence[-2])
      return sequence