old_contents: from flask import render_template
  
  from app.h5 import h5
  
  
  @h5.route('/preview', methods=['GET'])
  def preview():
      return render_template('h5/preview.html')
  
new_contents: from flask import render_template
  
  from app.h5 import h5
  
  
  @h5.route('/preview2/<stock_or_code>', methods=['GET'])
  @h5.route('/preview/<stock_or_code>', methods=['GET'])
  def preview(stock_or_code):
      print(stock_or_code)
      return render_template('h5/preview.html')
  
subject: fix bug