function normalizeLinguistName(d) {
  // Names are case-insensitive, so we lowercase.
  // For an example, see `SnipMate` which is included as an alias, but using
  // `snipmate` or `SNIPMATE` also highlights.
  //
  // Spaces in names are turned into dashes.
  // For example `DNS zone` can be used as `dns-zone`, not as `dns`, `dns_zone`,
  // or `dnszone`.
  const normal = d.toLowerCase().replace(/ /g, '-')
  assert.ok(/^[-_a-z\d.#+'*()/]+$/.test(normal), normal)
  return normal
}
@param {string} d
  Name to normalize.
@returns {string}
  Normalized name.