def METHOD_NAME(env: "Environment", value: str) -> bool:
    """Check if a test exists by name. Useful if a test may be
    optionally available.
    .. code-block:: jinja
        {% if 'loud' is test %}
            {% if value is loud %}
                {{ value|upper }}
            {% else %}
                {{ value|lower }}
            {% endif %}
        {% else %}
            {{ value }}
        {% endif %}
    .. versionadded:: 3.0
    """
    return value in env.tests