input: Your task is to write a function in Python that generates a random string of a specified length. The function should return the generated string. Here is the function signature and example usage:
  
  
  import random
  
  def generate_string(string_length):
      """Generate a random string of the specified length.
      >>> generate_string(10)
      'gH3jK9lP2q'
      >>> generate_string(5)
      'A8fR5'
      """
      random_characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
      random_string = ''.join(random.choices(random_characters, k=string_length))
      return random_string
  
output:     random_characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
      random_string = ''.join(random.choices(random_characters, k=string_length))
      return random_string