while (true) {
      if (peek == null) {
        peek = readToken()
        if (skipCommasAndWhitespace()) break // We peeked a scheme name followed by ','.
        eqCount = skipAll('='.code.toByte())
      }
      if (eqCount == 0) break // We peeked a scheme name.
      if (eqCount > 1) return // Unexpected '=' characters.
      if (skipCommasAndWhitespace()) return // Unexpected ','.