# subtleties of matching
abc		&	xabcy	abc
a\(b\)?c\1d	b	acd
aBc		i	Abc	Abc
a[Bc]*d		i	abBCcd	abBCcd
0[[:upper:]]1	&i	0a1	0a1
0[[:lower:]]1	&i	0A1	0A1
a[^b]c		&i	abc
a[^b]c		&i	aBc
a[^b]c		&i	adc	adc
[a]b[c]		-	abc	abc
[a]b[a]		-	aba	aba
[abc]b[abc]	-	abc	abc
[abc]b[abd]	-	abd	abd
a(b?c)+d	-	accd	accd
(wee|week)(knights|night)	-	weeknights	weeknights
(we|wee|week|frob)(knights|night|day)	-	weeknights	weeknights
a[bc]d		-	xyzaaabcaababdacd	abd
a[ab]c		-	aaabc	abc
abc		s	abc	abc
a*		&	b	@b