---input---
f"""{x
+1}"""

---tokens---
'f'           Literal.String.Affix
'"""'         Literal.String.Double
'{'           Literal.String.Interpol
'x'           Name
'\n'          Text.Whitespace

'+'           Operator
'1'           Literal.Number.Integer
'}'           Literal.String.Interpol
'"""'         Literal.String.Double
'\n'          Text.Whitespace
