input: Write a function to compute the factorial of a given number using an iterative approach. The function should take a single integer as input and return the factorial of that number. If the given number is 0 or 1, the function should return 1.
  
  assert factorial(7)==5040
  assert factorial(0)==1
  assert factorial(1)==1
  assert factorial(5)==120
  assert factorial(4)==24
output: def factorial(n):
      result = 1
      for i in range(2, n + 1):
          result *= i
      return result