WP_Block_Styles_Registry::register( string|string[] $block_name, array $style_properties ): bool

64	public function register( $block_name, $style_properties ) {65 66		if ( ! is_string( $block_name ) && ! is_array( $block_name ) ) {67			_doing_it_wrong(68				__METHOD__,69				__( 'Block name must be a string or array.' ),70				'6.6.0'71			);72			return false;73		}74 75		if ( ! isset( $style_properties['name'] ) || ! is_string( $style_properties['name'] ) ) {76			_doing_it_wrong(77				__METHOD__,78				__( 'Block style name must be a string.' ),79				'5.3.0'80			);81			return false;82		}83 84		if ( str_contains( $style_properties['name'], ' ' ) ) {85			_doing_it_wrong(86				__METHOD__,87				__( 'Block style name must not contain any spaces.' ),88				'5.9.0'89			);90			return false;91		}92 93		$block_style_name = $style_properties['name'];94		$block_names      = is_string( $block_name ) ? array( $block_name ) : $block_name;95 96		// Ensure there is a label defined.97		if ( empty( $style_properties['label'] ) ) {98			$style_properties['label'] = $block_style_name;99		}100 101		foreach ( $block_names as $name ) {102			if ( ! isset( $this->registered_block_styles[ $name ] ) ) {103				$this->registered_block_styles[ $name ] = array();104			}105			$this->registered_block_styles[ $name ][ $block_style_name ] = $style_properties;106		}107 108		return true;109	}