Fix error in len(depset) example

RELNOTES: none
PiperOrigin-RevId: 217511487

site/docs/skylark/performance.md

diff --git a/site/docs/skylark/performance.md b/site/docs/skylark/performance.md
index a115934..e050304 100644
--- a/site/docs/skylark/performance.md
+++ b/site/docs/skylark/performance.md
@@ -105,7 +105,7 @@
   files = depset(...)
 
   # Bad, has to iterate over entire depset to get length
-  if len(files) == 0:
+  if len(files) != 0:
     args.add("--files")
     args.add_all(files)