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

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

## Create your data model

Then you declare your data model as a class that inherits from `BaseModel`.

Use standard Python types for all the attributes:

{* ../../docs_src/body/tutorial001_py310.py hl[5:9] *}

          break
      k -= 1
      continue
    previous_end_line = lines.get('end') or start_line

  return result_store_links


def indent_xml(elem, level=0) -> None:
  """Indents and newlines the XML for better output."""
  indent_str = '\n' + level * '  '
  if len(elem):  # pylint: disable=g-explicit-length-test  # `if elem` not valid
    if not elem.text or not elem.text.strip():

If you pass a custom list of `servers` and there's a `root_path` (because your API lives behind a proxy), **FastAPI** will insert a "server" with this `root_path` at the beginning of the list.

For example:

{* ../../docs_src/behind_a_proxy/tutorial003.py hl[4:7] *}

Will generate an OpenAPI schema like:

```JSON hl_lines="5-7"

   * @since 11.0
   */
  @Override
  public ImmutableListMultimap<V, K> inverse() {
    ImmutableListMultimap<V, K> result = inverse;
    return (result == null) ? (inverse = invert()) : result;
  }

  private ImmutableListMultimap<V, K> invert() {
    Builder<V, K> builder = builder();
    for (Entry<K, V> entry : entries()) {
      builder.put(entry.getValue(), entry.getKey());
    }

   * LinkedHashMap because one target node may be mapped to both a predecessor and a successor. A
   * LinkedHashMap combines two such edges into a single node-value pair, even though the edges may
   * not have been inserted consecutively.
   */
  @CheckForNull private final List<NodeConnection<N>> orderedNodeConnections;

  private int predecessorCount;
  private int successorCount;

  private DirectedGraphConnections(

		}
		if retentionPermErr != ErrNone {
			return mode, retainDate, legalHold, retentionPermErr
		}
		return rMode, rDate, legalHold, ErrNone
	}
	if replica { // replica inherits retention metadata only from source
		return "", objectlock.RetentionDate{}, legalHold, ErrNone
	}
	if !retentionRequested && retentionCfg.Validity > 0 {
		if retentionPermErr != ErrNone {

 * provided {@code standardAddAll} method.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations
 * invoke methods, they invoke methods on the {@code ForwardingNavigableSet}.
 *

 * provided {@code standardPutAll} method.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations
 * invoke methods, they invoke methods on the {@code ForwardingMap}.
 *
 * <p>Each of the {@code standard} methods, where appropriate, use {@link Objects#equal} to test

        return higherIndex;
      }
    },
    /**
     * Return {@code ~insertionIndex}, where {@code insertionIndex} is defined as the point at which
     * the key would be inserted into the list: the index of the next higher element in the list, or
     * {@code list.size()} if there is no such element.
     *

		return errors.Join(errs...)
	}

	return errors.Join(errs...)
}

// syncHostIPSets is called after the host node ipset has been created (or found + flushed)
// during initial snapshot creation, it will insert every snapshotted pod's IP into the set.
//
// The set does not allow dupes (obviously, that would be undefined) - but in the real world due to misconfigured