input: Write a python function to generate the first n numbers in the Fibonacci sequence.
  assert fibonacciSequence(5) == [0, 1, 1, 2, 3]
  assert fibonacciSequence(7) == [0, 1, 1, 2, 3, 5, 8]
  assert fibonacciSequence(10) == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
output: def fibonacciSequence(n):
      if n <= 0:
          return []
      sequence = [0]
      if n > 1:
          sequence.append(1)
      for i in range(2, n):
          sequence.append(sequence[-1] + sequence[-2])
      return sequence