**projects depend on**. That's very difficult to manage. And you would probably end up running some projects with some **incompatible versions** of the packages, and not knowing why something isn't working.

Also, depending on your operating system (e.g. Linux, Windows, macOS), it could have come with Python already installed. And in that case it probably had some packages pre-installed with some specific versions **needed by your system**. If you install packages in the global Python environment,...

        new File("/home/build/x/y/z.jar").toURI(),
        ClassPath.getClassPathEntry(new File("/home/build/outer.jar"), "x/y/z.jar").toURI());
    assertEquals(
        "/home/build/x y.jar",
        ClassPath.getClassPathEntry(new File("/home/build/outer.jar"), "x y.jar").getFile());
  }

  public void testGetClassPathFromManifest_nullManifest() {
    assertThat(ClassPath.getClassPathFromManifest(new File("some.jar"), null)).isEmpty();
  }

        * `implicit`
        * `clientCredentials`
        * `authorizationCode`
    * But there is one specific "flow" that can be perfectly used for handling authentication in the same application directly:
        * `password`: some next chapters will cover examples of this.
* `openIdConnect`: has a way to define how to discover OAuth2 authentication data automatically.

And these same full-stack generators were the base of the [**FastAPI** Project Generators](project-generation.md){.internal-link target=_blank}.

/// info

Flask-apispec was created by the same Marshmallow developers.

///

/// check | Inspired **FastAPI** to

Generate the OpenAPI schema automatically, from the same code that defines serialization and validation.

///

### Certificate Renewal { #certificate-renewal }

At some point in the future, each certificate would **expire** (about 3 months after acquiring it).

And then, there would be another program (in some cases it's another program, in some cases it could be the same TLS Termination Proxy) that would talk to Let's Encrypt, and renew the certificate(s).

The **Advanced User Guide** builds on this one, uses the same concepts, and teaches you some extra features.

But you should first read the **Tutorial - User Guide** (what you are reading right now).

* `internal`: Internal
    * Use this for changes that only affect how the repo is managed. For example upgrades to internal dependencies, changes in GitHub Actions or scripts, etc.

/// tip

        netdfs.DfsInfo1 info1 = new netdfs.DfsInfo1();
        info1.entry_path = "test_path";

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        // Create buffer for encoding - initially allocate some space
        byte[] encodeBuffer = new byte[1024];
        NdrBuffer dst = new NdrBuffer(encodeBuffer, 0);
        info1.encode(dst);

        ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());

{* ../../docs_src/dependencies/tutorial008_an_py39.py hl[18:19,26:27] *}

The same way, you could have some dependencies with `yield` and some other dependencies with `return`, and have some of those depend on some of the others.

And you could have a single dependency that requires several other dependencies with `yield`, etc.

   *
   * @return the next two bytes of the input stream, interpreted as an unsigned 16-bit integer in
   *     little-endian byte order
   * @throws IOException if an I/O error occurs
   */
  @CanIgnoreReturnValue // to skip some bytes
  @Override
  public int readUnsignedShort() throws IOException {
    byte b1 = readAndCheckByte();
    byte b2 = readAndCheckByte();

    return Ints.fromBytes((byte) 0, (byte) 0, b2, b1);
  }