function set( label ) {
	/* eslint-disable no-invalid-this */
	if ( !isString( label ) ) {
		throw new TypeError( format( 'invalid assignment. `%s` must be a string. Value: `%s`.', 'label', label ) );
	}
	if ( label !== this._label ) {
		debug( 'Current value: %s.', this._label );

		this._label = label;
		debug( 'New Value: %s.', this._label );

		this.emit( 'change' );
	}
}
Sets the data label.

@private
@param {string} label - data label
@throws {TypeError} must be a string
@returns {void}