> Modern versions of Python have support for **"asynchronous code"** using something called **"coroutines"**, with **`async` and `await`** syntax.

That should make more sense now. ✨

All that is what powers FastAPI (through Starlette) and what makes it have such an impressive performance.

## Very Technical Details

!!! warning
    You can probably skip this.

By the last <a href="https://www.jetbrains.com/research/python-developers-survey-2018/#development-tools" class="external-link" target="_blank">Python Developer Survey</a>, that covers about 80% of the users.

import javax.annotation.CheckForNull;

/**
 * {@link Error} variant of {@link java.util.concurrent.ExecutionException}. As with {@code
 * ExecutionException}, the error's {@linkplain #getCause() cause} comes from a failed task,
 * possibly run in another thread. That cause should itself be an {@code Error}; if not, use {@code
 * ExecutionException} or {@link UncheckedExecutionException}. This allows the client code to

if [[ "$TFCI_ARTIFACT_FINAL_GCS_ENABLE" == 1 ]]; then
  gcloud auth activate-service-account --key-file="$TFCI_ARTIFACT_FINAL_GCS_SA_PATH"

  # $TF_VER_FULL will resolve to e.g. "2.15.0-rc2". Since $TF_VER_FULL comes
  # from get_versions.sh, which must be run *after* update_version.py, FINAL_URI
  # can't be set inside the rest of the _upload envs.
  FINAL_URI="$TFCI_ARTIFACT_FINAL_GCS_URI/$TF_VER_FULL"

import javax.annotation.CheckForNull;

/**
 * Unchecked variant of {@link java.util.concurrent.ExecutionException}. As with {@code
 * ExecutionException}, the exception's {@linkplain #getCause() cause} comes from a failed task,
 * possibly run in another thread.
 *
 * <p>{@code UncheckedExecutionException} is intended as an alternative to {@code

!!! check
    Notice that the value your function received (and returned) is `3`, as a Python `int`, not a string `"3"`.

    So, with that type declaration, **FastAPI** gives you automatic request <abbr title="converting the string that comes from an HTTP request into Python data">"parsing"</abbr>.

## Data validation

The main thing you need to run a **FastAPI** application (or any other ASGI application) in a remote server machine is an ASGI server program like **Uvicorn**, this is the one that comes by default in the `fastapi` command.

There are several alternatives, including:

* <a href="https://www.uvicorn.org/" class="external-link" target="_blank">Uvicorn</a>: a high performance ASGI server.

Luego vas al mostrador 🔀, a la tarea inicial que ya está terminada ⏯, recoges las hamburguesas 🍔, les dices gracias y las llevas a la mesa. Eso termina esa fase / tarea de interacción con el mostrador ⏹. Eso a su vez, crea una nueva tarea, "comer hamburguesas" 🔀 ⏯, pero la anterior de "conseguir hamburguesas" está terminada ⏹.

### Hamburguesas Paralelas

Ahora imagina que estas no son "Hamburguesas Concurrentes" sino "Hamburguesas Paralelas".

              sneakyThrow(new SomeCheckedException());
              throw new AssertionError(); // unreachable
            }
          }
        };

    // The first time, the sneakily-thrown exception comes out
    try {
      iter.hasNext();
      fail("No exception thrown");
    } catch (Exception e) {
      if (!(e instanceof SomeCheckedException)) {
        throw e;
      }
    }

  }

  /**
   * Either writes this request to [sink] or measures its content length. We have one method
   * do double-duty to make sure the counting and content are consistent, particularly when it comes
   * to awkward operations like measuring the encoded length of header strings, or the
   * length-in-digits of an encoded integer.
   */
  private fun writeOrCountBytes(
    sink: BufferedSink?,
    countBytes: Boolean,