BF: Wrap imports of optional deps in try-except block

Author: moloney

nipype/interfaces/dcmstack.py

@@ -10,11 +10,16 @@
                                     traits, 
                                     BaseInterface,
                                    )
-import dicom
-import dcmstack
-from dcmstack.dcmmeta import NiftiWrapper
 import nibabel as nb
 
+have_dcmstack = True
+try:
+    import dicom
+    import dcmstack
+    from dcmstack.dcmmeta import NiftiWrapper
+except ImportError:
+    have_dcmstack = False
+
 def sanitize_path_comp(path_comp):
     result = []
     for char in path_comp: