function get() {
	/* eslint-disable no-invalid-this */
	var max;
	var len;
	var d;
	var i;

	if ( this._yMax === null ) {
		len = this._data.length;
		max = NINF;
		for ( i = 0; i < len; i++ ) {
			d = this._data[ i ];
			if ( this._isDefined( d ) && d !== PINF && d > max ) {
				max = d;
			}
		}
		return max;
	}
	return this._yMax;
}
Returns the maximum value of the y-axis domain.

@private
@returns {(FiniteNumber|null)} maximum value of the y-axis domain