int
           | &#39;real&#39; constraint
           | &#39;vector&#39; constraint &#39;[&#39; expression &#39;]&#39;
           | &#39;ordered&#39; &#39;[&#39; expression &#39;]&#39;
           | &#39;positive_ordered&#39; &#39;[&#39; expression &#39;]&#39;
           | &#39;simplex&#39; &#39;[&#39; expression &#39;]&#39;
           | &#39;unit_vector&#39; &#39;[&#39; expression &#39;]&#39;
           | &#39;row_vector&#39; constraint &#39;[&#39; expression &#39;]&#39;
           | &#39;matrix&#39; constr