get_term

 *
 * There are two hooks, one is specifically for each term, named 'get_term', and
 * the second is for the taxonomy name, 'term_$taxonomy'. Both hooks gets the
 * term object, and the taxonomy name as parameters. Both hooks are expected to
 * return a Term object.
 *
 * {@see 'get_term'} hook - Takes two parameters the term Object and the taxonomy name.
 * Must return term object. Used in get_term() as a catch-all filter for every
 * $term.
 *
 * {@see 'get_$taxonomy'} hook - Takes two parameters the term Object and the taxonomy
 * name. Must return term object. $taxonomy will be the taxonomy name, so for
 * example, if 'category', it would be 'get_category' as the filter name. Useful
 * for custom taxonomies or plugging into default taxonomies.
 *
 * @todo Better formatting for DocBlock
 *
 * @since 2.3.0
 * @since 4.4.0 Converted to return a WP_Term object if `$output` is `OBJECT`.
 *              The `$taxonomy` parameter was made optional.
 *
 * @see sanitize_term_field() The $context param lists the available values for get_term_by() $filter param.
 *
 * @param int|WP_Term|object $term     If integer, term data will be fetched from the database,
 *                                     or from the cache if available.
 *                                     If stdClass object (as in the results of a database query),
 *                                     will apply filters and return a `WP_Term` object with the `$term` data.
 *                                     If `WP_Term`, will return `$term`.
 * @param string             $taxonomy Optional. Taxonomy name that `$term` is part of.
 * @param string             $output   Optional. The required return type. One of OBJECT, ARRAY_A, or ARRAY_N, which
 *                                     correspond to a WP_Term object, an associative array, or a numeric array,
 *                                     respectively. Default OBJECT.
 * @param string             $filter   Optional. How to sanitize term fields. Default 'raw'.
 * @return WP_Term|array|WP_Error|null WP_Term instance (or array) on success, depending on the `$output` value.
 *                                     WP_Error if `$taxonomy` does not exist. Null for miscellaneous failure.
 */
function get_term( $term, $taxonomy = '', $output = OBJECT, $filter = 'raw' ) {
	if ( empty( $term ) ) {
		return new WP_Error( 'invalid_term', __( 'Empty Term.' ) );
	}

	if ( $taxonomy && ! taxonomy_exists( $taxonomy ) ) {
		return new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
	}

	if ( $term instanceof WP_Term ) {
		$_term = $term;
	} elseif ( is_object( $term ) ) {
		if ( empty( $term->filter ) || 'raw' === $term->filter ) {
			$_term = sanitize_term( $term, $taxonomy, 'raw' );
			$_term = new WP_Term( $_term );
		} else {
			$_term = WP_Term::get_instance( $term->term_id );
		}
	} else {
		$_term = WP_Term::get_instance( $term, $taxonomy );
	}

	if ( is_wp_error( $_term ) ) {
		return $_term;
	} elseif ( ! $_term ) {
		return null;
	}

	// Ensure for filters that this is not empty.
	$taxonomy = $_term->taxonomy;

	/**
	 * Filters a taxonomy term object.
	 *
	 * @since 2.3.0
	 * @since 4.4.0 `$_term` is now a `WP_Term` object.