4-level laser inversion and saturation including degeneracies. Repeat the pumping and saturation calculations for a 4-level laser system given during the lecture (and also described in the section 6. 2 of the Siegman's book) assuming the same pumping rate Rp and relaxation rates yi as in the text, but taking into account the existence of degeneracies g1 and g2 of the lower and upper energy levels and their effect on the definitions of W12, W21, and AN21