Build an extension definition.

    This is the reverse of :func:`parse_extension_item`.

def build_extension_item(name: str, parameters: List[ExtensionParameter]) -> str:
    """
    Build an extension definition.

    This is the reverse of :func:`parse_extension_item`.

    """
    return "; ".join(
        [name]
        + [
            # Quoted strings aren't necessary because values are always tokens.
            name if value is None else f"{name}={value}"
            for name, value in parameters
        ]
    )