$ 'main' (--)
 \
  \
   \----9(!d!)-9(!t!)-------(t)(d){bottle_or_bottles}----[ of beer on the wall, ]o----(t)(d){bottle_or_bottles}--------------------------\
                        /                                                                                                                 \
                       /                                                                                                                   |
    /-----------------/                                                                                                                    |
   /                                                                                                                                       |
   |                                                                                                                                       |
   |     #----o[\n\.llaw eht no reeb fo selttob 99 ,erom emos yub dna erots eht ot oG]----\                                                |
   |                                                                                       \                                               |
   |                                                                                        >--q1(d)----\                                  |
   |                                                                                       /             \                                /
   |                                                                                      /               >--q0(t)----o[\n\.reeb fo ]----/
   |                                                                                     /               /
   |     /--------------------------------------o[ ,dnuora ti ssap dna nwod eno ekaT]-------------------/
   |    /
   |    |
   |    |                /----(d)1s(!d!)----------------------(t)(d){bottle_or_bottles}----[ of beer on the wall.\n\\n\]o----\
   |    \               /                                /                                                                    \
   |     \----0(d)q----<                                /                                                                     |
   |                    \                              /                                                                      |
   |                     \----9(!d!)----(t)1s(!t!)----/                                                                       |
   |                                                                                                                          |
   \                                                                                                                         /
    \-----------------------------------------------------------------------------------------------------------------------/



$ 'bottle_or_bottles' ( t d -- )
 \                                                                                   /----------------[s]o--------#
  \                                                                                 /            /           /
   \                             /----(d)o--------------------[ bottle]o----(t)0q--<            /           /   
    \                           /                        /                          \          /           /
     \----(!d!)(!t!)----(t)0g--<                        /                            \-(d)1q--<           /
                                \                      /                                       \         /
                                 \----(t)o----(d)o----/                                         \-------/