fficient, Hoyer sparsity, oracle SNR, and the <span class="emphasis"><em>M</em></span><sub>2</sub><span class="emphasis"><em>M</em></span><sub>4</sub> SNR
          estimator to <code class="computeroutput"><span class="identifier">tools</span><span class="special">/</span><span class="identifier">signal_statistics</span><span class="special">.</span><span class="identifier">hpp</span></code>.
        </li>
<li class="listitem">
          Add total variation, l0, l1, l2, and sup norms, as well as correspond