input: from typing import List
  
  def rectangle_area(dimensions: List[int]) -> int:
      """Given a list of two integers representing the length and width of a rectangle, 
      calculate and return the area of the rectangle.
      >>> rectangle_area([5, 10])
      50
      >>> rectangle_area([3, 4])
      12
      """
output:     return dimensions[0] * dimensions[1]