input: 
  def get_current_datetime() -> str:
      """
      Create a web API using Flask to provide the current date and time in the format YYYY-MM-DD HH:MM:SS.
      >>> get_current_datetime()
      '2023-04-01 14:25:30'
      """
  
output:     
      from datetime import datetime
      return datetime.now().strftime('%Y-%m-%d %H:%M:%S')
  