input: from typing import List
  
  def calculate_product_of_evens(numbers: List[int]) -> int:
      """Given a list of integers, this function should return the product of all the even numbers in the list. If there are no even numbers, the function should return 1.
      >>> calculate_product_of_evens([1, 2, 3, 4])
      8
      >>> calculate_product_of_evens([1, 3, 5, 7])
      1
      """
output:     product = 1
      for num in numbers:
          if num % 2 == 0:
              product *= num
      return product