* whose edges have associated non-unique values.
 *
 * <p>A graph is composed of a set of nodes and a set of edges connecting pairs of nodes.
 *
 * <p>There are three primary interfaces provided to represent graphs. In order of increasing
 * complexity they are: {@link Graph}, {@link ValueGraph}, and {@link Network}. You should generally

  /**
   * A buffer for [upstreamReader] to use when pulling bytes from upstream. Only the
   * [upstreamReader] thread may access this buffer.
   */
  val upstreamBuffer = Buffer()

  /** True if there are no further bytes to read from [upstream]. Guarded by this. */
  var complete = (upstream == null)

  /** The most recently read bytes from [upstream]. This is a suffix of [file]. Guarded by this. */
  val buffer = Buffer()

   *
   * <p>Whenever possible, it is preferable to test directly for some observable change resulting
   * from GC, as with {@link #awaitClear}. Because there are no guarantees for the order of GC
   * finalization processing, there may still be some unfinished work for the GC to do after this
   * method returns.
   *
   * <p>This method does not create any memory pressure as would be required to cause soft

It is designed to be very simple to use, and to make it very easy for any developer to integrate other components with **FastAPI**.

## What is "Dependency Injection"

**"Dependency Injection"** means, in programming, that there is a way for your code (in this case, your *path operation functions*) to declare things that it requires to work and use: "dependencies".

Because of this, **FastAPI** itself provides an alternative API documentation (using ReDoc), which you can access at <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>:

<img src="/img/tutorial/path-params/image02.png">

  @J2ktIncompatible
  @GwtIncompatible // threads
  private static boolean trySetName(String threadName, Thread currentThread) {
    /*
     * setName should usually succeed, but the security manager can prohibit it. Is there a way to
     * see if we have the modifyThread permission without catching an exception?
     */
    try {
      currentThread.setName(threadName);
      return true;
    } catch (SecurityException e) {

# Templates

You can use any template engine you want with **FastAPI**.

A common choice is Jinja2, the same one used by Flask and other tools.

There are utilities to configure it easily that you can use directly in your **FastAPI** application (provided by Starlette).

## Install dependencies

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and install `jinja2`:

<div class="termy">

        }
        /*
         * This transform exists solely to shrink the size of the fastutil jar from 25MB to 1.7MB.
         * The keys to the map parameter are used as the names of the files to which to apply the transform - there is only one entry.
         * It would perhaps be better to do this more selectively instead of applying this transform so broadly and having
         * it just no-op in most cases.
         */

   *       that's not annotated nullable should throw {@link NullPointerException}.
   *   <li>If there is any non-private constructor or non-private static factory method declared by
   *       {@code cls}, all non-private instance methods will be checked too using the instance
   *       created by invoking the constructor or static factory method.
   *   <li>If there is any non-private constructor or non-private static factory method declared by

        assertEscaping(xmlEscaper, "\uFFFD", ch);
      }
    }

    // Test _all_ allowed characters (including surrogate values).
    for (char ch = 0x20; ch <= 0xFFFD; ch++) {
      // There are a small number of cases to consider, so just do it manually.
      if (ch == '&') {
        assertEscaping(xmlEscaper, "&amp;", ch);
      } else if (ch == '<') {
        assertEscaping(xmlEscaper, "&lt;", ch);