FIX: check value type against tuple, not Tuple

Author: effigies

nipype/interfaces/afni/preprocess.py

@@ -2582,7 +2582,7 @@ class Volreg(AFNICommand):
     output_spec = VolregOutputSpec
 
     def _format_arg(self, name, trait_spec, value):
-        if name == 'in_weight_volume' and not isinstance(value, Tuple):
+        if name == 'in_weight_volume' and not isinstance(value, tuple):
             value = (value, 0)
         return super(Volreg, self)._format_arg(name, trait_spec, value)