title: What is difference between Map.fetch(key, value) and Map.fetch!(key, value)
body: <p><a href="https://hexdocs.pm/elixir/Map.html#fetch/2" rel="nofollow noreferrer">https://hexdocs.pm/elixir/Map.html#fetch/2</a> and <a href="https://hexdocs.pm/elixir/Map.html#fetch!/2" rel="nofollow noreferrer">https://hexdocs.pm/elixir/Map.html#fetch!/2</a> are slightly different but there is no discussion as to what is different.</p>
  
  <p>The document does mention the first is "inlined by the compiler" and the later is exception raised. </p>
  
  <p>Is there a rule of thumb I should have on when to use one and not the other, vice versa?</p>
  
  <p>regards</p>