a	[a]
 	  a	[  a]
 	,a	[][a]
 	 , a	[ ][ a]
 	a,b	[a][b]
 	a,b,c	[a][b][c]
 	""	[]
 	"abc"	[abc]
 	"a""b"	[a"b]
 	"a","b"	[a][b]
 	"a,b"	[a,b]
 	""""	["]
 	""""""	[""]
 	"""x"""	["x"]
 	,,""	[][][]
 	a''b	[a''b]
 	,,	[][][]
 	a,	[a][]
 	"",	[][]
 	,	[][]
 	"abc",def	[abc][def]