- setup:
  cleanup:
  args:
  input:    |
            |     1
            |    / \
            |   2   3
            |  /   / \
            | 4   5   6
            |  \
            |   7
  output:   |
            |     27
            |    /  \
            |   26  25
            |  /   /  \
            | 24  23  22
            |  \
            |  21