* expected</i>, but not absolutely required, to have the following properties:
     *
     * <ul>
     *   <li>Its execution does not cause any observable side effects.
     *   <li>The computation is <i>consistent with equals</i>; that is, {@link Objects#equals
     *       Objects.equals}{@code (k1, k2) &&} {@link Objects#equals Objects.equals}{@code (v1,

     * expected</i>, but not absolutely required, to have the following properties:
     *
     * <ul>
     *   <li>Its execution does not cause any observable side effects.
     *   <li>The computation is <i>consistent with equals</i>; that is, {@link Objects#equals
     *       Objects.equals}{@code (k1, k2) &&} {@link Objects#equals Objects.equals}{@code (v1,

evaluated exactly once, in source order, upon entering the "select" statement.
The result is a set of channels to receive from or send to,
and the corresponding values to send.
Any side effects in that evaluation will occur irrespective of which (if any)
communication operation is selected to proceed.
Expressions on the left-hand side of a RecvStmt with a short variable declaration
or assignment are not yet evaluated.