<<A+B
  ^ unterminated heredoc; can't find string "A" anywhere before EOF
#{C + "#{"}
           ^ unterminated string meets end of file
           ^ unexpected end-of-input, assuming it is closing the parent top level context
           ^ expected a `}` to close the embedded expression
      ^ unterminated string; expected a closing delimiter for the interpolated string
           ^ expected a `}` to close the embedded expression

