if (peek == null) {
      skipCommasAndWhitespace()
      peek = readToken()
      if (peek == null) return
    }

    val schemeName = peek

    // Read a token68, a sequence of parameters, or nothing.
    val commaPrefixed = skipCommasAndWhitespace()
    peek = readToken()
    if (peek == null) {
      if (!exhausted()) return // Expected a token; got something else.