title: What exactly self and -> int mean in this python snippet def line1(self, arr: List[int], a: int, b: int, c: int) -> int:
body: <p>For the pythons snippet below,</p>
  <pre><code>def line1(self, arr: List[int], a: int, b: int, c: int) -&gt; int:
  </code></pre>
  <p>what does  -&gt; int mean? what is the purpose of b:int then? also what does self mean?</p>