class_docstr: Create output filenames that work nicely with multiple input files from
  multiple directories (processing multiple subjects with one command)
  
  Use information from input files, out_dir and out_fnames to generate
  correct outputs which can come from long lists of multiple or single
  inputs.
code: def create_directories(self):
      for outputs in self.outputs:
          for output in outputs:
              directory = os.path.dirname(output)
              if not (directory == "" or os.path.exists(directory)):
                  os.makedirs(directory)
  
imports: import inspect
  import itertools
  import numpy
  import os
  from glob import glob
  from dipy.workflows.base import get_args_default
label_desc: Use image node_id 7 for calling the IOIterator obj's underlying member method code with example usage: obj.create_directories() without return types