# Primeros Pasos { #first-steps }

El archivo FastAPI más simple podría verse así:

{* ../../docs_src/first_steps/tutorial001_py39.py *}

Copia eso en un archivo `main.py`.

Ejecuta el servidor en vivo:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:solid">main.py</u>

    protected long allRecordCount;

    /** Relation type for the record count (e.g., "eq", "gte"). */
    protected String allRecordCountRelation;

    /** Total number of pages based on record count and page size. */
    protected int allPageCount;

    /** Flag indicating whether a next page exists. */
    protected boolean existNextPage;

    /** Flag indicating whether a previous page exists. */

                        }
                    } else {
                        pending.add(element);
                    }
                }

                List<Plugin> result = new ArrayList<>(src.size() + tgt.size());
                for (Map.Entry<Object, Plugin> entry : master.entrySet()) {
                    List<Plugin> pre = predecessors.get(entry.getKey());
                    if (pre != null) {

        // Should have both consumer POM (no classifier) and build POM (with "build" classifier)
        Collection<Artifact> artifacts = result.getArtifacts();
        assertEquals(3, artifacts.size()); // original jar + consumer pom + build pom

        assertTrue(artifacts.stream().anyMatch(a -> "pom".equals(a.getExtension()) && "".equals(a.getClassifier())));
        assertTrue(

  private static final int ENDPOINT = -2;

  /**
   * Contains the link pointers corresponding with the entries, in the range of [0, size()). The
   * high 32 bits of each long is the "prev" pointer, whereas the low 32 bits is the "succ" pointer
   * (pointing to the next entry in the linked list). The pointers in [size(), entries.length) are
   * all "null" (UNSET).
   *

/**
 * GWT emulation of {@link ImmutableEnumSet}. The type parameter is not bounded by {@code Enum<E>}
 * to avoid code-size bloat.
 *
 * @author Hayward Chan
 */
final class ImmutableEnumSet<E> extends ForwardingImmutableSet<E> {
  static <E> ImmutableSet<E> asImmutable(Set<E> delegate) {
    switch (delegate.size()) {
      case 0:
        return ImmutableSet.of();
      case 1:

   * size() as a hint only.
   *
   * @param delta the difference between the true size of the collection and the values returned by
   *     the size method
   */
  public static <T extends @Nullable Object> Collection<T> misleadingSizeCollection(int delta) {
    // It would be nice to be able to return a real concurrent
    // collection like ConcurrentLinkedQueue, so that e.g. concurrent

        listen  [::]:9000;
        server_name  localhost;

         # To allow special characters in headers
         ignore_invalid_headers off;
         # Allow any size file to be uploaded.
         # Set to a value such as 1000m; to restrict file size to a specific value
         client_max_body_size 0;
         # To disable buffering
         proxy_buffering off;

        location / {

    }

    protected void assertProblemFree(SimpleProblemCollector collector) {
        assertEquals(0, collector.getErrors().size(), "Expected no errors");
        assertEquals(0, collector.getWarnings().size(), "Expected no warnings");
        assertEquals(0, collector.getFatals().size(), "Expected no fatals");
    }

    @SuppressWarnings("SameParameterValue")
    protected void assertCollectorState(

    }

    val factory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm())
    factory.init(trustStore)
    val result = factory.trustManagers!!
    check(result.size == 1 && result[0] is X509TrustManager) {
      "Unexpected trust managers: ${result.contentToString()}"
    }

    val trustManager = result[0] as X509TrustManager

    return when {