^                                        ^
      / \                                      / \
     /set\                                    /do \
    ^-----^                                  ^-----^
   /a\   /"\                                /a\   / \
   ---  ^---                                ---  /   \
       / \                                      /     \
      /   \                                    /=      \
     /line \                                  ^---------^
     -------                                 / \       / \
                                            /   \      ---^
                                           /?    \       / \ 
                                          ^-------^      ---^
                                         /!\     / \       / \ 
                                        ^---    /out\      ---^ 
                                       / \      -----^       / \ 
                                      /   \         / \      ---^ 
                                     /     \       /arg\       / \
                                    /       \     ^-----^     /set\
                                   /         \   /a\   /4\   ^-----^
                                  /?          \  ---   ---  /a\   /"\      
                                 ^-------------^            ---  ^--- 
                                / \           / \               / \
                               /   \         /out\             /   \
                              /     \        -----^           /line \
                             /       \           / \          -------
                            /=        \         /arg\
                           ^-----------^       ^-----^
                          / \         / \     /a\   /2\
                         /arg\       /arg\    ---   ---
                        ^-----^     ^-----^   
                       /a\   /1\   /a\   /2\  
                       ---   ---   ---   ---