title: Why doesn't PyCharm show me type hint validation errors
body: <p>I'm using PyCharm 2021.2.2 (Community Edition). I'm learning about <a href="https://fastapi.tiangolo.com/python-types/" rel="nofollow noreferrer">Python Type Hints from the FastAPI docs</a>. When I write a function like this</p>
  <pre><code>def get_name_with_age(name: str, age: int) -&gt; str:
      name_with_age = name + &quot; is this old: &quot; + age
      return 10
  </code></pre>
  <p><a href="https://www.jetbrains.com/help/pycharm/type-hinting-in-product.html" rel="nofollow noreferrer">Shouldn't Pycharm warn me</a> that I'm attempting to return an int but the function is supposed to return a string? And / or shouldn't it warn me that I can't concatenate a string with an int? Pycharm doesn't warn me about either of these things..</p>
  <p><a href="https://i.stack.imgur.com/V24Hp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/V24Hp.png" alt="enter image description here" /></a></p>