---input---
"a\nz"
"a\az"
"a\xffz"
"a\u1234z"
"a\000z"
"a\u{0}z"
"a\u{10AfF9}z"

---tokens---
'"'           Literal.String.Double
'a'           Literal.String.Double
'\\n'         Literal.String.Escape
'z'           Literal.String.Double
'"'           Literal.String.Double
'\n'          Text.Whitespace

'"'           Literal.String.Double
'a'           Literal.String.Double
'\\a'         Literal.String.Escape
'z'           Literal.String.Double
'"'           Literal.String.Double
'\n'          Text.Whitespace

'"'           Literal.String.Double
'a'           Literal.String.Double
'\\xff'       Literal.String.Escape
'z'           Literal.String.Double
'"'           Literal.String.Double
'\n'          Text.Whitespace

'"'           Literal.String.Double
'a'           Literal.String.Double
'\\u1234'     Literal.String.Escape
'z'           Literal.String.Double
'"'           Literal.String.Double
'\n'          Text.Whitespace

'"'           Literal.String.Double
'a'           Literal.String.Double
'\\000'       Literal.String.Escape
'z'           Literal.String.Double
'"'           Literal.String.Double
'\n'          Text.Whitespace

'"'           Literal.String.Double
'a'           Literal.String.Double
'\\u{0}'      Literal.String.Escape
'z'           Literal.String.Double
'"'           Literal.String.Double
'\n'          Text.Whitespace

'"'           Literal.String.Double
'a'           Literal.String.Double
'\\u{10AfF9}' Literal.String.Escape
'z'           Literal.String.Double
'"'           Literal.String.Double
'\n'          Text.Whitespace