Let \(f _ { n } , f\) be analytic functions on the unit disk D. Show that the following are equivalent.
\(f _ { n } ( z )\) converges to f(z) uniformly on compact subsets in D.
\(\int _ { | z | = r } | f _ { n } ( z ) - f ( z ) | | d z |\) converges to 0 if \(0 < r < 1\)