Description:
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The following pages in the documentation states that "SplSubject" and "SplObserver" are classes when in fact they are interfaces.

http://php.net/class.splsubject
http://php.net/class.splobserver


Reproduce code:
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1: echo class_exists( 'SplSubject' ) ? 'SplSubject is a class' : 'SplSubject is NOT a class';

2: echo interface_exists( 'SplSubject' ) ? 'SplSubject is an interface' : 'SplSubject is NOT an interface';

3: echo class_exists( 'SplObserver' ) ? 'SplObserver is a class' : 'SplObserver is NOT a class';

4: echo interface_exists( 'SplObserver' ) ? 'SplObserver is an interface' : 'SplObserver is NOT an interface';

Expected result:
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1: SplSubject is NOT a class
 
2: SplSubject is an interface

3: SplObserver is NOT a class

4: SplObserver is an interface

Actual result:
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1: SplSubject is NOT a class
 
2: SplSubject is an interface

3: SplObserver is NOT a class

4: SplObserver is an interface