Update app.py

app.py

@@ -87,7 +87,7 @@ def sample_at_length(l:int, seed:int):
     l = int(l)
  
     # Sample the angles
-    s = sampling.sample_simple("wukevin/foldingdiff_cath", n=1, sweep_lengths=(l, l+1))[0]
+    s = sampling.sample_simple("wukevin/foldingdiff_cath", n=1, sweep_lengths=(l, l+1)).pop()
 
     # Create a PDB file after building out the structure in 3D coordinates
     outdir = os.path.join(os.getcwd(), "output")