A method called$$subtract$$which receives another$$MyDate$$object as a parameter.$$ This method must subtract the received$$MyDate$$object from the$$MyDate object on which the method is called.$$ Subtraction should happen as follows:

The calculated year should be the average value of the current object$$s year and that of the received$$MyDate$$object$$s year, e$.$g$.$ if the $2$ years are $2020$ and $2010,$ the new year value should be $2015.$The month of the received$$MyDate$$should be subtracted from the current object.$$ If the calculated month is less than $0,$ it should default to a value of $1.$The day of the received$$MyDate$$should be subtracted from the current object.$$ If the calculated day is less than $0,$ it should default to a value of $1.$

An override of the str method that outputs a$$MyDate$$in the format day month name year, e$.$g$.1$ January $1970.$