old_contents: from flask import Flask, send_file
  app = Flask(__name__)
  
  @app.route("/hello")
  def hello():
      return "Hello World from Flask in a uWSGI Nginx Docker container with \
       Python 3.6 (from the example template)"
  
  @app.route("/")
  def main():
      return send_file('./static/index.html')
  
  # Everything not declared before (not a Flask route / API endpoint)...
  @app.route('/<path:path>')
  def route_frontend(path):
      # ...could be a static file needed by the front end that
      # doesn't use the `static` path (like in `<script src="bundle.js">`)
      file_path = './static/' + path
      if os.path.isfile(file_path):
          return send_file(file_path)
      # ...or should be handled by the SPA's "router" in front end
      else:
          return send_file('./static/index.html')
  
  if __name__ == "__main__":
      app.run(host='0.0.0.0', debug=True, port=80)
  
new_contents: import os
  
  from flask import Flask, send_file
  app = Flask(__name__)
  
  
  @app.route("/hello")
  def hello():
      return "Hello World from Flask in a uWSGI Nginx Docker container with \
       Python 3.6 (from the example template)"
  
  
  @app.route("/")
  def main():
      return send_file('./static/index.html')
  
  
  # Everything not declared before (not a Flask route / API endpoint)...
  @app.route('/<path:path>')
  def route_frontend(path):
      # ...could be a static file needed by the front end that
      # doesn't use the `static` path (like in `<script src="bundle.js">`)
      file_path = './static/' + path
      if os.path.isfile(file_path):
          return send_file(file_path)
      # ...or should be handled by the SPA's "router" in front end
      else:
          return send_file('./static/index.html')
  
  
  if __name__ == "__main__":
      app.run(host='0.0.0.0', debug=True, port=80)
  
subject: Fix not imported os and format code