title: Flask - Error: While importing 'app', an ImportError was raised
body: <p>I'm trying to get a hello world flask app running with Python 3.9.7.</p>
  <p>Folder structure:<br>
  py-flask/<br>
  app.py<br>
  README.md<br></p>
  <p>Content of app.py:<br></p>
  <pre><code>from flask import flask
  
  app = flask(__name__)
  
  @app.route(&quot;/&quot;)
  def index():
      return &quot;Hello Wolford&quot;
  
  @app.route(&quot;/greeting/&quot;)
  def greeting():
      return &quot;Nice to see you&quot;
  </code></pre>
  <p>When I am in the py-flask directory, and I try running the app, I get:<br>
  <code>Error: While importing 'app', an ImportError was raised.</code><br></p>
  <p>I've tried <code>python3 -m flask run</code> and <code>flask run</code> neither works.<br></p>
  <p>Any thoughts on what I could be doing wrong?<br>
  pip list if its useful:<br></p>
  <pre><code>Package       Version
  ------------- -------
  cachelib      0.4.1
  click         8.0.3
  Flask         2.0.2
  Flask-Session 0.4.0
  itsdangerous  2.0.1
  Jinja2        3.0.2
  MarkupSafe    2.0.1
  pip           21.2.3
  setuptools    57.4.0
  Werkzeug      2.0.2
  </code></pre>