edefined generators. It is a very
          trivial generator that simply produces spaces. It is the equivalent to
          writing <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="char">' '</span><span class="special">)</span></code>, or simply
          <code class="computeroutput"><span class="char">' '</span></code>. It has been implemented
          for similarity with the corresponding predefined <code class="computeroutput"><span class="ident