a=>{<<b
      ^ unterminated heredoc; can't find string "b" anywhere before EOF
    ^~~ unexpected heredoc beginning; expected a key in the hash pattern
      ^ unterminated heredoc; can't find string "b" anywhere before EOF
    ^~~ expected a label as the key in the hash pattern
   ^ expected a `}` to close the pattern expression
       ^ unexpected heredoc ending, expecting end-of-input
       ^ unexpected heredoc ending, ignoring it