class_docstr: Holds the ops for each dtypes signature like ('ff->f', func1)
  and allows to do look ups for these
code: def _sig_str_to_tuple(self, sig):
      sig = sig.replace(" ", "")
      toks = sig.split("->")
      if len(toks) != 2:
          raise ValueError(f"signature {sig} for dtypes is invalid")
      else:
          ins, outs = toks
      return ins, outs
  
imports: import re
  import numpy
  import cupy
  import cupy._core._routines_manipulation
  from cupy._core._dtype import get_dtype, _raise_if_invalid_cast
  from cupy._core import internal
label_desc: Use image node_id 2 for calling the _OpsRegister obj's underlying member method code with example usage: obj._sig_str_to_tuple(sig) and returns: ins,  outs