Allow ntuple to be used with string values

Author: rwightman

timm/models/layers/helpers.py

@@ -9,7 +9,7 @@
 # From PyTorch internals
 def _ntuple(n):
     def parse(x):
-        if isinstance(x, collections.abc.Iterable):
+        if isinstance(x, collections.abc.Iterable) and not isinstance(x, str):
             return x
         return tuple(repeat(x, n))
     return parse