input: Write a python function to find factors of a number.
  assert find_factors(60)==[2, 3, 4, 5, 6, 10, 12, 15, 20, 30]
  assert find_factors(45)==[3, 5, 9, 15]
  assert find_factors(100)==[2, 4, 5, 10, 20, 25, 50]
output: def find_factors(n):
      factors = []
      for i in range(2, n):
          if n % i == 0:
              factors.append(i)
      return factors