gistfile1.txt

>> Regexp.compile('(')
RegexpError: premature end of regular expression: /(/
	from (irb):13:in `initialize'
	from (irb):13:in `compile'
	from (irb):13
	from :0

>> Regexp.compile('foo{1|2}')
(irb):14: warning: regexp has invalid interval
(irb):14: warning: regexp has `}' without escape
=> foo{12}

>> Regexp.compile('foo{1|2}'); $!.backtrace
(irb):15: warning: regexp has invalid interval
(irb):15: warning: regexp has `}' without escape
NoMethodError: undefined method `backtrace' for nil:NilClass
	from (irb):15
	from :0