###
6.4.2 #include from a string or expression (eval)

The template:

      #attr $y = "Let's go $voom!"
      #include source=$y
      #include raw source=$y
      #include source="Bam!  Bam!"

The output:

      % voom="VOOM" x.py --env
      Let's go VOOM!Let's go $voom!Bam!  Bam!

The generated code:

      write(self._includeCheetahSource(VFS(SL,"y",1), trans=trans,
          includeFrom="str", raw=0, includeID="481020889808.74"))
      write(self._includeCheetahSource(VFS(SL,"y",1), trans=trans,
          includeFrom="str", raw=1, includeID="711020889808.75"))
      write(self._includeCheetahSource("Bam!  Bam!", trans=trans,
          includeFrom="str", raw=0, includeID="1001020889808.75"))

Later in the generated class:

      y = "Let's go $voom!"