enh: add s3 datagrabber example

several examples here: https://github.com/kellyhennigan/cueexp_scripts/blob/25372d4f221762af6d79d1af67a8570f2c546b20/svmrfe/venv/lib64/python2.7/site-packages/nipype/interfaces/tests/test_io.py

Author: satra

nipype/interfaces/io.py

@@ -829,7 +829,22 @@ class S3DataGrabber(LibraryBaseInterface, IOBase):
         "template" uses regex style formatting, rather than the
         glob-style found in the original DataGrabber.
 
+        Examples
+        --------
+
+        >>> s3grab = S3DataGrabber(infields=['subj_id'], outfields=["func", "anat"]))
+        >>> s3grab.inputs.bucket = 'openneuro'
+        >>> s3grab.inputs.sort_filelist = True
+        >>> s3grab.inputs.template = '*' 
+        >>> s3grab.inputs.anon = True
+        >>> s3grab.inputs.bucket_path = 'ds000101/ds000101_R2.0.0/uncompressed/' 
+        >>> s3grab.inputs.local_directory = '/tmp' 
+        >>> s3grab.inputs.field_template = {'anat': '%s/anat/%s_T1w.nii.gz', 'func': '%s/func/%s_task-simon_run-1_bold.nii.gz'} 
+        >>> s3grab.inputs.template_args = {'anat': [['subj_id', 'subj_id']], 'func': [['subj_id', 'subj_id']]} 
+        >>> s3grab.inputs.subj_id = 'sub-01'
+        >>> s3grab.run()  # doctest: +SKIP
     """
+    
     input_spec = S3DataGrabberInputSpec
     output_spec = DynamicTraitedSpec
     _always_run = True