diff --git a/dalle2_pytorch/vqgan_vae.py b/dalle2_pytorch/vqgan_vae.py
index 4d08389..1c073fd 100644
--- a/dalle2_pytorch/vqgan_vae.py
+++ b/dalle2_pytorch/vqgan_vae.py
@@ -68,8 +68,8 @@ def group_dict_by_key(cond, d):
         return_val[ind][key] = d[key]
     return (*return_val,)
 
-def string_begins_with(prefix, str):
-    return str.startswith(prefix)
+def string_begins_with(prefix, string_input):
+    return string_input.startswith(prefix)
 
 def group_by_key_prefix(prefix, d):
     return group_dict_by_key(partial(string_begins_with, prefix), d)