documentclass{article}
usepackage[ansinew]{inputenc}
usepackage[T1]{fontenc}

begin{document}
setlengthparindent{0pt}
huge

A°@ 1

{catcode`°12 xdefstr{A°@ 1}}
str

scantokensexpandafter{strempty}

defaaa{afterassignmentbbbletccc= }
defbbb{%
  ifxcccnil
     END
     letnextrelax
  else
     [scantokensexpandafter{cccempty}]letnextaaa
  fi
  next
}
expandafteraaastrnil

end{document}