title: Python: How to create a function? e.g. f(x) = ax^2
body: <p>I want to have some sort of reference to a function but I do not know if I need to use a <code>def f(x)</code> or a <code>lambda</code> of some kind.</p>
  
  <p>For instance I'd like to <code>print f(3)</code> and have it output <code>9a</code>, or is this not how python works?</p>
  
  <p><strong>Second question</strong>: Assuming I have a working function, how do I return the <code>degree</code> of it?</p>