[Tutor] Improving My Simple Game Code for Speed, Memory and Learning

[WolfRage]

I had an issue in my logic and again my named variables provided for 
confusion, so I had to add some comments to clarify.

I got much closer by editing my code like this:

def drop_floating_nodes0(self):
         i = self.rows
         # first_zero_row serves as memory for how far to drop non-zero 
values
         first_zero_row = None
         for col_list in self.transposed_grid:
             while True:
                 # Low is on Top, High is on Bottom
                 low, high = col_list[i - 2: i]  # Goes Up the Rows
                 if high.value == 0:
                     if low.value != 0:
                         if first_zero_row is None:
                             high.value = low.value
                             low.value = 0
                             first_zero_row = low
                         else:
                             first_zero_row.value = low.value
                             low.value = 0
                             high.value = 0
                             first_zero_row = low
                     else:
                         if first_zero_row is None:
                             first_zero_row = high
                 i -= 1
                 if i == 1:
                     i = self.rows
                     first_zero_row = None
                     break

But it still fails as you can see here from the output:

| 20 | 19 | 11 | 20 |
| 11 |  5 |  5 | 11 |
| 19 |  5 | 11 | 11 |
| 19 | 20 | 20 |  5 |
| 11 | 19 | 19 | 11 |
| 20 |  6 |  6 | 11 |
| 19 | 11 |  5 | 20 |
| 11 | 20 | 11 | 20 |
After Eliminations
| 20 |  0 | 11 |  0 |
|  0 |  0 |  0 |  0 |
|  0 |  0 | 11 |  0 |
|  0 |  0 |  0 |  0 |
|  0 |  0 |  0 |  0 |
| 20 |  6 |  6 |  0 |
| 19 | 11 |  5 |  0 |
| 11 | 20 | 11 | 20 |
After Drops
|  0 |  0 |  0 |  0 |
|  0 |  0 |  0 |  0 |
|  0 |  0 | 11 |  0 |
|  0 |  0 |  0 |  0 |
| 20 |  0 | 11 |  0 |
| 20 |  6 |  6 |  0 |
| 19 | 11 |  5 |  0 |
| 11 | 20 | 11 | 20 |