input: Write a python function to calculate the power of a number using iterative multiplication.
  assert power(2, 3) == 8
  assert power(5, 0) == 1
  assert power(7, 2) == 49
  assert power(10, 5) == 100000
output: def power(base, exponent):
      result = 1
      for _ in range(exponent):
          result *= base
      return result