<a href="http:&#x2F;&#x2F;programmers.stackexchange.com&#x2F;questions&#x2F;142192&#x2F;why-would-a-programmer-want-to-separate-implementation-from-interface" rel="nofollow">http:&#x2F;&#x2F;programmers.stackexchange.com&#x2F;questions&#x2F;142192&#x2F;why-wo...</a>