title: Why the compose and identity method is omitted in Bifunction interface Java 8?
body: <p>I have just started reading Java 8 concepts while reading I found something which was not convincing me enough that is the omission of <code>compose</code> and <code>identity</code> method in <code>BiFunction</code> Interface. As far as I could read from Java 8 documentation I could see <code>Bifunction</code> seems to be in same as <code>Function</code> interface expect that it takes an additional arguments so in such case <code>Bifunction</code> should have all features as that of <code>Function</code> interface, but it is not so.</p>
  
  <p>Hence, can anyone help me find reason behind omitting these methods?</p>