---
title: protocols (latest version)
description: API reference for qiskit_bosons.protocols in the latest version of qiskit-bosons
source: https://quantum.cloud.ibm.com/docs/en/api/qiskit-bosons/protocols
---

# Protocols

This module provides the protocols used throughout the package.

A [`typing.Protocol`](https://docs.python.org/3/library/typing.html#typing.Protocol) is an interface that a class can fulfill structurally, without explicitly inheriting from it. For example, any class that implements a `__len__` method satisfies [`Sized`](https://docs.python.org/3/library/typing.html#typing.Sized), whether or not it says so anywhere in its class hierarchy.

The protocols here follow the same idea, each centered on a small set of dunder-style methods. A class implementing them thereby satisfies the protocol and becomes usable wherever it is expected, without any explicit registration.

| Protocol                                                                                                                                                                  | Methods                                                    | Helper functions                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [`SupportsCommutators`](/docs/api/qiskit-bosons/protocols-supports-commutators#qiskit_bosons.protocols.SupportsCommutators "qiskit_bosons.protocols.SupportsCommutators") | `_commutator_`, `_anti_commutator_`, `_double_commutator_` | [`commutator()`](/docs/api/qiskit-bosons/operators-library-commutator#qiskit_bosons.operators.library.commutator "qiskit_bosons.operators.library.commutator"), [`anti_commutator()`](/docs/api/qiskit-bosons/operators-library-anti-commutator#qiskit_bosons.operators.library.anti_commutator "qiskit_bosons.operators.library.anti_commutator"), [`double_commutator()`](/docs/api/qiskit-bosons/operators-library-double-commutator#qiskit_bosons.operators.library.double_commutator "qiskit_bosons.operators.library.double_commutator") |

|                                                                                                                                                                                               |                                                                    |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------ |
| [`SupportsCommutators`](/docs/api/qiskit-bosons/protocols-supports-commutators#qiskit_bosons.protocols.SupportsCommutators "qiskit_bosons.protocols.SupportsCommutators")(\*args, \*\*kwargs) | A Protocol indicating support for efficient commutator generation. |