code: def none_or_dtype(dtype):
      """Check None presence before type casting."""
      local_type = dtype
  
      def inner(value):
          if value in ["None", "none"]:
              return "None"
          return local_type(value)
  
      return inner
  
file_path: dipy/dipy/workflows/base.py
imports: import argparse
  import inspect
  from dipy.workflows.docstring_parser import NumpyDocString
label_desc: Use image node_id 2 for calling a global function with example usage: none_or_dtype(dtype) and returns: inner, local_type, str