Given a variable called $year, create a PHP program that will print out " is a leap year" or " is not a leap year",. Use the following rules to determine if a year is a leap year: if the year is divisible by 4 then it is a leap year, unless it is also divisible by 100 (in which case it is not a leap year), unless it is divisible by 400 (in which case it is a leap year.