input: from flask import Flask
  import datetime
  
  app = Flask(__name__)
  
  @app.route('/datetime')
  def get_datetime():
      """ Create a web API with Python and Flask to give the current date and time.
      The endpoint should return the current datetime in the format "YYYY-MM-DD HH:MM:SS".
      Example:
      Request to /datetime
      Response: "2023-10-05 14:30:45"
      """
      return datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
  
  if __name__ == '__main__':
      app.run()
output:     return datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")