---input---
f"mapping is { {a:b for (a, b) in ((1, 2), (3, 4))} }"

---tokens---
'f'           Literal.String.Affix
'"'           Literal.String.Double
'mapping is ' Literal.String.Double
'{'           Literal.String.Interpol
' '           Text.Whitespace
'{'           Punctuation
'a'           Name
':'           Punctuation
'b'           Name
' '           Text.Whitespace
'for'         Keyword
' '           Text.Whitespace
'('           Punctuation
'a'           Name
','           Punctuation
' '           Text.Whitespace
'b'           Name
')'           Punctuation
' '           Text.Whitespace
'in'          Operator.Word
' '           Text.Whitespace
'('           Punctuation
'('           Punctuation
'1'           Literal.Number.Integer
','           Punctuation
' '           Text.Whitespace
'2'           Literal.Number.Integer
')'           Punctuation
','           Punctuation
' '           Text.Whitespace
'('           Punctuation
'3'           Literal.Number.Integer
','           Punctuation
' '           Text.Whitespace
'4'           Literal.Number.Integer
')'           Punctuation
')'           Punctuation
'}'           Punctuation
' '           Text.Whitespace
'}'           Literal.String.Interpol
'"'           Literal.String.Double
'\n'          Text.Whitespace