## Pydantic

All the data validation is performed under the hood by <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a>, so you get all the benefits from it. And you know you are in good hands.

You can use the same type declarations with `str`, `float`, `bool` and many other complex data types.

Several of these are explored in the next chapters of the tutorial.

## Order matters

  // Clients can use the appropriate server address as per the CIDR that they match.
  // In case of multiple matches, clients should use the longest matching CIDR.
  // The server returns only those CIDRs that it thinks that the client can match.
  // For example: the master will return an internal IP CIDR only, if the client reaches the server using an internal IP.

                    if ( transport.isDisconnected() || transport.getRemoteHostName() == null ) {
                        /*
                         * Tree/session thinks it is connected but transport disconnected
                         * under it, reset tree to reflect the truth.
                         */
                        log.debug("Disconnecting failed tree and session");

      /*
       * The GuardedBy checker warns us that we're not holding cancellationDelegate.lock. But in
       * fact we are holding it because it is the same as this.lock, which we know we are holding,
       * thanks to @GuardedBy above. (cancellationDelegate.lock is initialized to this.lock in the
       * call to `new SupplantableFuture` below.)
       */
      @SuppressWarnings("GuardedBy")

   * has elapsed after the entry's creation, or the most recent replacement of its value.
   *
   * <p>When {@code duration} is zero, this method hands off to {@link #maximumSize(long)
   * maximumSize}{@code (0)}, ignoring any otherwise-specified maximum size or weight. This can be
   * useful in testing, or to disable caching temporarily without a code change.
   *

   */
  @CheckForNull
  protected abstract char[] escape(int cp);

  /**
   * Returns the escaped form of a given literal string.
   *
   * <p>If you are escaping input in arbitrary successive chunks, then it is not generally safe to
   * use this method. If an input string ends with an unmatched high surrogate character, then this
   * method will throw {@link IllegalArgumentException}. You should ensure your input is valid <a

     * lying about the fields below on the grounds that we always initialize them just after the
     * constructor -- an example of the kind of lying that our hypothetical bytecode rewriter would
     * already have to deal with, thanks to DI frameworks that perform field and method injection,
     * frameworks like Android that define post-construct hooks like Activity.onCreate, etc.
     */

    Crc32cHasher() {
      super(16);
    }

    private boolean finished = false;

    /*
     * This trick allows us to avoid having separate states for "first four ints" and "all other
     * four int chunks."  The state we want after the first four bytes is
     *
     * crc0 = ~int0
     * crc1 = int1
     * crc2 = int2
     * crc3 = int3
     *

//
//	<chunk-size-as-hex> + ";chunk-signature=" + <signature-as-hex> + "\r\n" + <payload> + "\r\n"
//
// First, we read the chunk size but fail if it is larger
// than 16 MiB. We must not accept arbitrary large chunks.
// One 16 MiB is a reasonable max limit.
//
// Then we read the signature and payload data. We compute the SHA256 checksum
// of the payload and verify that it matches the expected signature value.
//

	// the output and parse it from there.
	filter, exitStr := newExitCodeFilter(os.Stdout)
	args += "; echo -n " + exitStr + "$?"

	cmd := adbCmd("exec-out", args)
	cmd.Stdout = filter
	// If the adb subprocess somehow hangs, go test will kill this wrapper
	// and wait for our os.Stderr (and os.Stdout) to close as a result.
	// However, if the os.Stderr (or os.Stdout) file descriptors are
	// passed on, the hanging adb subprocess will hold them open and