./testdata/language-features/guard/guard10.reject.lc:2:1:
unexpected '|'
expecting "class", "data", "infix", "infixl", "infixr", "instance", "type", ''', backquoted ident, end of input, expression, lambda, lhs, literal, lowercase ident, operator definition, pattern, rest of expression, symbols, typed ident, or uppercase ident