input: from typing import List
  
  def generate_string(string_length: int) -> str:
      """ Generate a random string of given length using alphanumeric characters.
      >>> generate_string(10)
      'aB3defGhI9'
      >>> generate_string(5)
      '1A2B3'
      """
output:     import random
      import string
      
      return ''.join(random.choices(string.ascii_letters + string.digits, k=string_length))