---input---
root:x:0:
sudo:x:1:syslog,user
syslog:x:2:
#adm:x:3:

user:x:1000

---tokens---
'root'        Text
':'           Punctuation
'x'           Literal.String
':'           Punctuation
'0'           Literal.Number
':'           Punctuation
'\n'          Text.Whitespace

'sudo'        Text
':'           Punctuation
'x'           Literal.String
':'           Punctuation
'1'           Literal.Number
':'           Punctuation
'syslog,user' Text
'\n'          Text.Whitespace

'syslog'      Text
':'           Punctuation
'x'           Literal.String
':'           Punctuation
'2'           Literal.Number
':'           Punctuation
'\n'          Text.Whitespace

'#adm:x:3:'   Comment
'\n'          Text.Whitespace

'\n'          Text.Whitespace

'user'        Text
':'           Punctuation
'x'           Literal.String
':'           Punctuation
'1000'        Literal.Number
'\n'          Text.Whitespace