---input---
def f(using y: Char = if true then 'a' else 2): Int = ???

---tokens---
'def'         Keyword
' '           Text
'f'           Name.Function
'('           Punctuation
'using'       Keyword
' '           Text
'y'           Name
':'           Punctuation
' '           Text
'Char'        Name.Class
' '           Text
'='           Operator
' '           Text
'if'          Keyword
' '           Text
'true'        Keyword.Constant
' '           Text
'then'        Keyword
' '           Text
"'a'"         Literal.String.Char
' '           Text
'else'        Keyword
' '           Text
'2'           Literal.Number.Integer
')'           Punctuation
':'           Punctuation
' '           Text
'Int'         Name.Class
' '           Text
'='           Operator
' '           Text
'???'         Operator
'\n'          Text
