This problem concerns a discrete-time filter with a real-valued impulse response h[n]. Determine whether the following statement is true or false: 

Statement: If the group delay of the filter is a constant for 0 < ω < π, then the impulse response must have the property that either 

h[n] = h[M – n]

or

h[n] = − h[M – n],

 where M is an integer. 

If you believe that the statement is true, clearly show your reasoning. If you believe that it is false, provide a counterexample