1 Returns a copy of +self+ with trailing substring <tt>suffix</tt> removed:
3 'hello'.delete_suffix('llo') # => "he"
4 'hello'.delete_suffix('hel') # => "hello"
5 'тест'.delete_suffix('ст') # => "те"
6 'こんにちは'.delete_suffix('ちは') # => "こんに"
8 Related: String#delete_suffix!, String#delete_prefix.
