def calculate_page_offset(page_size, page_number):
  """Calculates the page offset for a given page size and number.

  Args:
    page_size: int, the size of the amount of items for a page.
    page_number: int, the page number to calculate an offset for.

  Returns:
    The calculated integer value for the offset.
  """
  return (page_number - 1) * page_size