input: Write a python function to find the factors of a given number.
  assert find_factors(15) == [1, 3, 5, 15]
  assert find_factors(28) == [1, 2, 4, 7, 14, 28]
  assert find_factors(1) == [1]
output: def find_factors(n):
      factors = []
      for i in range(1, n + 1):
          if n % i == 0:
              factors.append(i)
      return factors