I have a set: 

```
{'6HUP ILE 228 D', '6HUP PHE 289 B', '6HUP PRO 233 D', '6HUP MET 286 E', '6HUP THR 237 A', '6HUP MET 236 D', '6HUP MET 261 B', '6HUP PHE 289 E', '6HUP LEU 285 B', '6HUP LEU 232 D', '6HUP TYR 210 D', '6HUP MET 236 A', '6HUP MET 261 E', '6HUP LEU 232 A', '6HUP THR 262 B', '6HUP VAL 203 D', '6HUP SER 205 D', '6HUP PRO 233 A', '6HUP SER 206 D', '6HUP HIS 102 D', '6HUP PHE 100 D', '6HUP SER 159 D', '6HUP LEU 269 D', '6HUP ASN 60 C', '6HUP MET 286 B', '6HUP PHE 77 C', '6HUP LEU 285 E', '6HUP TYR 160 D', '6HUP GLN 204 D', '6HUP ASN 265 E', '6HUP TYR 58 C', '6HUP THR 262 E', '6HUP ASN 265 B', '6HUP ILE 228 A'}

```

Using a snippet of my set, I'd like to sort each element in the following way: 

from:

```
 {'6HUP ILE 228 D', '6HUP ASN 60 C','6HUP PHE 289 B', '6HUP PRO 233 D', '6HUP MET 286 E', '6HUP THR 237 A','6HUP ILE 228 A','6HUP THR 262 B','6HUP PHE 77 C'}

```

to : 

```
{'6HUP ILE 228 A', '6HUP THR 237 A','6HUP THR 262 B','6HUP PHE 289 B','6HUP ASN 60 C','6HUP PHE 77 C','6HUP ILE 228 D','6HUP PRO 233 D','6HUP MET 286 E'}

```

Essentially, I'd like to sort it by index[3](the one letter code at the end of each entry, A, B, C ,D, E ) and index[2] (ie, 60, 228, 237, 262) with index[3] being the first priority and index[2] being the second priority. A Lowest to Highest, B Lowest to Highest, C Lowest to Highest, etc. 

Thanks!