code: def _dec_register_stf(func):
      """Register slice time function in module dictionary"""
      name = func.__name__
      SLICETIME_FUNCTIONS[name] = func
      if name.startswith("st_"):
          short_name = name[3:]
          if short_name in SLICETIME_FUNCTIONS:
              raise ValueError(
                  f"Duplicate short / long function name {short_name}"
              )
          SLICETIME_FUNCTIONS[short_name] = func
      return func
  
file_path: nipy/nipy/algorithms/slicetiming/timefuncs.py
imports: import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: _dec_register_stf(func) and returns: func