input: Write a python function to create the project structure and initialize a Flask application using the given commands.
  assert create_flask_app_structure() == ["app", "app/static", "app/templates", "app/app.py", "app/templates/base.html", "app/models.py", "app/views.py", "app/routes.py", "app/static/style.css"]
  assert initialize_flask_app() == ["pip install flask", "pip install flask-sqlalchemy", "python manage.py db init", "python manage.py db migrate", "python manage.py db upgrade", "python app.py"]
output: import os
  
  def create_flask_app_structure():
      structure = [
          "app",
          "app/static",
          "app/templates",
          "app/app.py",
          "app/templates/base.html",
          "app/models.py",
          "app/views.py",
          "app/routes.py",
          "app/static/style.css"
      ]
      
      for path in structure:
          if '.' in path.split('/')[-1]:  # it's a file
              with open(path, 'w') as f:
                  pass
          else:  # it's a directory
              os.makedirs(path, exist_ok=True)
      
      return structure
  
  def initialize_flask_app():
      commands = [
          "pip install flask",
          "pip install flask-sqlalchemy",
          "python manage.py db init",
          "python manage.py db migrate",
          "python manage.py db upgrade",
          "python app.py"
      ]
      
      for command in commands:
          os.system(command)
      
      return commands