 vectors of
indices, for the three cases above:</p>
<pre><code>transformed data {
  int ns12[observed_12(y_observed)];
  int ns1[observed_1(y_observed)];
  int ns2[observed_2(y_observed)];
}</code></pre>
<p>You will need to write functions that pull out the count of
observations in each of the three sampling situations. This must be
done with functions because the result needs to go in top-level block
variable size declaration. Then the rest of transformed data just
fills in the values using three counters.