title: Docker NameError: name 'app' is not defined
body: <p>I am trying to make a Flask framework with python and trying to host it on Docker.</p>
  
  <pre><code>#importing dependencies
  from flask import Flask
  
  #initializing the name of the application
  app = Flask(__name__)
  
  @app.route('/')
  
  def hello(parameter_list):
      return 'Hello, this is my first try on Docker'
  
  if __name__ == "__main__":
      app.run(host="0.0.0.0", debug= True)
  </code></pre>
  
  <p>I am getting at Line 5 that <strong><em>name 'app' is not defined</em></strong></p>
  
  <p><img src="https://i.stack.imgur.com/PLWDL.png" alt="NameError"> 
  what should i do to remove this error?
  this is my first time asking a question over here, Please let me know if any other clarification is needed or suggestions for future posts.
  Thanks in advance</p>