title: Flask: How to serve static html?
body: <p>I am trying to serve a static html file, but returns a 500 error
  (a copy of editor.html is on .py and templates directory)
  This is all I have tried:</p>
  
  <pre><code>from flask import Flask
  app = Flask(__name__, static_url_path='/templates')
  @app.route('/')
  def hello_world():
      #return 'Hello World1!' #this works correctly!
      #return render_template('editor.html')
      #return render_template('/editor.html')
      #return render_template(url_for('templates', filename='editor.html'))
      #return app.send_static_file('editor.html') #404 error (Not Found)
      return send_from_directory('templates', 'editor.html')
  </code></pre>
  
  <p>This is the response:</p>
  
  <pre><code>Title: 500 Internal Server Srror
  
  Internal Server Error
  
  The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.
  </code></pre>