code: def _prepad_for_spline_filter(input, mode, cval):
      if mode in ["nearest", "grid-constant"]:
          # these modes need padding to get accurate boundary values
          npad = 12  # empirical factor chosen by SciPy
          if mode == "grid-constant":
              kwargs = dict(mode="constant", constant_values=cval)
          else:
              kwargs = dict(mode="edge")
          padded = cupy.pad(input, npad, **kwargs)
      else:
          npad = 0
          padded = input
      return padded, npad
  
imports: import math
  import warnings
  import cupy
  import numpy
  from cupy import _core
  from cupy._core import internal
  from cupy.cuda import runtime
  from cupyx import _texture
  from cupyx.scipy.ndimage import _util
  from cupyx.scipy.ndimage import _interp_kernels
  from cupyx.scipy.ndimage import _spline_prefilter_core
label_desc: Use image node_id 6 for calling a global function with example usage: _prepad_for_spline_filter(input, mode, cval) and returns: padded,  npad