addUpgrade(upgradeName) {
    this.upgrades[upgradeName].bought = true;
    this.subtractScore(this.upgrades[upgradeName].price);
    this.calculateUpgradeIncrease();
  }
// adds bought upgrades to player object
adds bought upgrades to player object
adds bought upgrades to player object
addUpgrade(upgradeName) {
    this.upgrades[upgradeName].bought = true;
    this.subtractScore(this.upgrades[upgradeName].price);
    this.calculateUpgradeIncrease();
  }
addUpgrade ( upgradeName ) { this . upgrades [ upgradeName ] . bought = true ; this . subtractScore ( this . upgrades [ upgradeName ] . price ) ; this . calculateUpgradeIncrease ( ) ; }
adds bought upgrades to player object
adds bought upgrades to player object