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