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