The input to a filter is a discrete-time, zero-mean, random process whose autocorrelation function is
for some constant such that 
We wish to filter this process so that the output of the filter is white. That is, we want the output, 
to have an autocorrelation function, 
(a) Find the transfer function of the filter. You may express your answer in terms of either a DTFT or a z-transform.
(b) Find the impulse response of the filter. For both parts, make sure your answer results in a causal filter.