Given three positive int
values, return their sum.
However, if any of the values is a teen—in the range 13..19, inclusive—then that value counts as 0,
except 15 and 16 do not count as a teens.
Complete and use the private helper method fixTeen
and use it to apply the teen rule so that you don't need to
repeat the same code three times.
You're challenge is to write tests for this problem described above.
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