assertThat(headers["e"]).isNull()
  }

  @Test fun iteratorOperator() {
    val headers = headersOf("a", "b", "c", "d")

    val pairs = mutableListOf<Pair<String, String>>()
    for ((name, value) in headers) {
      pairs += name to value
    }

    assertThat(pairs).containsExactly("a" to "b", "c" to "d")
  }

  @Test fun builderGetOperator() {
    val builder = Headers.Builder()
    builder.add("a", "b")

    }
  }
  return commaFound
}

private fun Buffer.startsWith(prefix: Byte): Boolean = !exhausted() && this[0] == prefix

/**
 * Reads a double-quoted string, unescaping quoted pairs like `\"` to the 2nd character in each
 * sequence. Returns the unescaped string, or null if the buffer isn't prefixed with a
 * double-quoted string.
 */
@Throws(EOFException::class)

) : RequestBody() {
  private val encodedNames: List<String> = encodedNames.toImmutableList()
  private val encodedValues: List<String> = encodedValues.toImmutableList()

  /** The number of key-value pairs in this form-encoded body. */
  @get:JvmName("size")
  val size: Int
    get() = encodedNames.size

  @JvmName("-deprecated_size")
  @Deprecated(
    message = "moved to val",

    printEvent("callStart");
  }

  @Override public void callEnd(Call call) {
    printEvent("callEnd");
  }

  ...
}
```

We can use this listener to race a pair of concurrent HTTP requests:

```java
Request washingtonPostRequest = new Request.Builder()
    .url("https://www.washingtonpost.com/")
    .build();
client.newCall(washingtonPostRequest).enqueue(new Callback() {

 *
 * Instances of this class are immutable. Use [Builder] to create instances.
 */
@Suppress("NAME_SHADOWING")
class Headers internal constructor(
  internal val namesAndValues: Array<String>,
) : Iterable<Pair<String, String>> {
  /** Returns the last value corresponding to the specified field, or null. */
  operator fun get(name: String): String? = commonHeadersGet(namesAndValues, name)

  /**

      }

    /**
     * Sets the public/private key pair used for this certificate. If unset a key pair will be
     * generated.
     */
    fun keyPair(keyPair: KeyPair) =
      apply {
        this.keyPair = keyPair
      }

    /**
     * Sets the public/private key pair used for this certificate. If unset a key pair will be
     * generated.
     */
    fun keyPair(

 * **Exchange** carries a single HTTP request/response pair.

 * **ExchangeFinder** chooses which connection carries each exchange. Where possible it will use the same connection for all exchanges in a single call. It prefers reusing pooled connections over establishing new connections.      

   */
  @Throws(IOException::class)
  private fun createTunnel(): Request? {
    var nextRequest = tunnelRequest!!
    // Make an SSL Tunnel on the first message pair of each SSL + proxy connection.
    val url = route.address.url
    val requestLine = "CONNECT ${url.toHostHeader(includeDefaultPort = true)} HTTP/1.1"
    while (true) {
      val source = this.source!!

   * }
   * ```
   *
   * The first property of the pair is the adapter that was used, the second property is the value.
   */
  internal val generalNameDnsName = Adapters.IA5_STRING.withTag(tag = 2L)
  internal val generalNameIpAddress = Adapters.OCTET_STRING.withTag(tag = 7L)
  internal val generalName: DerAdapter<Pair<DerAdapter<*>, Any?>> =
    Adapters.choice(
      generalNameDnsName,

  fun choice(vararg choices: DerAdapter<*>): DerAdapter<Pair<DerAdapter<*>, Any?>> {
    return object : DerAdapter<Pair<DerAdapter<*>, Any?>> {
      override fun matches(header: DerHeader): Boolean = true

      override fun fromDer(reader: DerReader): Pair<DerAdapter<*>, Any?> {
        val peekedHeader =
          reader.peekHeader()