Added reference to io

Author: adelavega

nipype/interfaces/io.py

@@ -40,6 +40,7 @@
 from .base import (
     TraitedSpec, traits, Str, File, Directory, BaseInterface, InputMultiPath,
     isdefined, OutputMultiPath, DynamicTraitedSpec, Undefined, BaseInterfaceInputSpec)
+from .bids_utils import BIDSDataGrabber
 
 try:
     import pyxnat