function get() {
	/* eslint-disable no-invalid-this */
	if ( isNull( this._ticks ) ) {
		if ( this._scale.ticks ) {
			return this._scale.ticks( this._numTicks, this._tickFormat );
		}
		return this._scale.domain();
	}
	return this._ticks.slice();
}
Returns the axis tick values.

@private
@returns {Array} ticks