Imagine you own a music shop that sells musical instruments. Create classes representing an inheritance hierarchy of musical instruments using the following UML diagram: $$ Employee discount is $25\%$ off the instrument $($Hint: $75\%$ of the initial cost$).$ If an item is onSale, then the price returned for getPrice$()$ should be $15\%$ off. Instrument boolean onSale; double price; int numInStock; double getPrice$()$ double applyEmloyeeDiscount$()$ void setOnSale$($boolean onSale$)$ boolean getOnSale$()$ void setPrice$($double price$)$ int getNumInStock$()$ void setNumInStock$($int numInStock$)$ StringInstrument int numStrings; int getNumStrings$()$ void setStrings$($int numStrings$)$ Guitar boolean isElectric; boolean getIsElectric$()$