$ zzextensao	foo.txt		#=> txt
$ zzextensao	foo.TXT		#=> TXT
$ zzextensao	foo.bar.txt	#=> txt
$ zzextensao	foo.bar.baz.txt	#=> txt
$ zzextensao	../../foo.txt	#=> txt
$ zzextensao	'~/foo.txt'	#=> txt
$ zzextensao	'foo bar.txt'	#=> txt
$ zzextensao	/etc/passwd
$ zzextensao	.vimrc
$ zzextensao	foo.
$

