* Compartir conexiones a bases de datos.
* Imponer seguridad, autenticación, requisitos de roles, etc.
* Y muchas otras cosas...

Todo esto, mientras minimizas la repetición de código.

## Primeros Pasos { #first-steps }

Veamos un ejemplo muy simple. Será tan simple que no es muy útil, por ahora.

Pero de esta manera podemos enfocarnos en cómo funciona el sistema de **Inyección de Dependencias**.

  <!-- proxies
   | This is a list of proxies which can be used on this machine to connect to the network.
   | Unless otherwise specified (by system property or command-line switch), the first proxy
   | specification in this list marked as active will be used.
   |-->
  <proxies>
    <!-- proxy
     | Specification for one proxy, to be used in connecting to the network.
     |
    <proxy>

			if err != nil {
				return toObjectErr(err, bucket, object)
			}
		}
		// Track total bytes read from disk and written to the client.
		totalBytesRead += partLength
		// partOffset will be valid only for the first part, hence reset it to 0 for
		// the remaining parts.
		partOffset = 0
	} // End of read all parts loop.
	// Return success.
	return nil
}

///

## Import Pydantic's `BaseModel` { #import-pydantics-basemodel }

First, you need to import `BaseModel` from `pydantic`:

{* ../../docs_src/body/tutorial001_py310.py hl[2] *}

## Create your data model { #create-your-data-model }

    Iterable<CharSource> cycle = Iterables.cycle(ImmutableList.of(source));
    CharSource concatenated = CharSource.concat(cycle);

    String expected = "abcdabcd";

    // read the first 8 chars manually, since there's no equivalent to ByteSource.slice
    // TODO(cgdecker): Add CharSource.slice?
    StringBuilder builder = new StringBuilder();

    Entry<K, V>[] entries =
        (n == entryArray.length) ? (Entry<K, V>[]) entryArray : createEntryArray(n);
    int hashCode = 0;

    for (int i = 0; i < n; i++) {
      // requireNonNull is safe because the first `n` elements have been filled in.
      Entry<K, V> entry = requireNonNull(entryArray[i]);
      K key = entry.getKey();
      V value = entry.getValue();
      checkEntryNotNull(key, value);

	}

	l.mutex.Lock()
	defer l.mutex.Unlock()
	var locksHeld int64
	if locksHeld, reply = l.lockMap[args.Resources[0]]; !reply {
		l.lockMap[args.Resources[0]] = ReadLock // No locks held on the given name, so claim (first) read lock
		reply = true
	} else if reply = locksHeld != WriteLock; reply { // Unless there is a write lock
		l.lockMap[args.Resources[0]] = locksHeld + ReadLock // Grant another read lock
	}
	return reply, nil
}

fi

CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher

# traverses directory structure from process work directory to filesystem root
# first directory with .mvn subdirectory is considered project base directory
find_maven_basedir() {

  if [ -z "$1" ]
  then
    echo "Path not specified to find_maven_basedir"
    return 1
  fi

// and skip a certain number of bytes.
type LimitWriter struct {
	io.Writer
	skipBytes int64
	wLimit    int64
}

// Write implements the io.Writer interface limiting upto
// configured length, also skips the first N bytes.
func (w *LimitWriter) Write(p []byte) (n int, err error) {
	n = len(p)
	var n1 int
	if w.skipBytes > 0 {
		if w.skipBytes >= int64(len(p)) {
			w.skipBytes -= int64(len(p))
			return n, nil
		}

    /*
     * These arrays are set up to test that the comparator compares bytes within a word in the
     * correct order—in order words, that it doesn't mix up big-endian and little-endian. The first
     * array has a smaller element at one index, and then the second array has a smaller element at
     * the next.
     */
    byte[] a0 = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 99, 15, 16, 17};