input: Write a python function to generate a random number within a given range using Flask.
  assert lower_limit <= generate_random_number({'lower_limit': 1, 'upper_limit': 10}) <= upper_limit
  assert lower_limit <= generate_random_number({'lower_limit': 100, 'upper_limit': 200}) <= upper_limit
  assert lower_limit <= generate_random_number({'lower_limit': -50, 'upper_limit': 50}) <= upper_limit
output: from flask import Flask, request, jsonify
  import random
  
  app = Flask(__name__)
  
  @app.route('/generate_random_number', methods=['POST'])
  def generate_random_number():
      data = request.json
      lower_limit = data.get('lower_limit')
      upper_limit = data.get('upper_limit')
      if lower_limit is None or upper_limit is None:
          return jsonify({'error': 'Please provide lower_limit and upper_limit'}), 400
      
      random_number = random.randint(lower_limit, upper_limit)
      return jsonify({'random_number': random_number})
  
  if __name__ == '__main__':
      app.run()