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