code: function warn(file, id, violation, suggestion, node, note, condition, joiner) {
    var warning
  
    if (suggestion) {
      if (!('join' in suggestion)) {
        suggestion = keys(suggestion)
      }
  
      if (isCapitalized(violation)) {
        suggestion = capitalize(suggestion)
      }
    }
  
    warning = message(violation, suggestion, condition, joiner)
    warning = file.warn(warning, node, [source, id].join(':'))
  
    if (note) {
      warning.note = note
    }
  }
docs: /* Warn on `file` about `violation` (at `node`) with
  `suggestion`s.