code: def _cv_init_level_set(init_level_set, image_shape, dtype=np.float64):
      """Generates an initial level set function conditional on input arguments."""
      if isinstance(init_level_set, str):
          if init_level_set == "checkerboard":
              res = _cv_checkerboard(image_shape, 5, dtype)
          elif init_level_set == "disk":
              res = _cv_large_disk(image_shape)
          elif init_level_set == "small disk":
              res = _cv_small_disk(image_shape)
          else:
              raise ValueError(
                  "Incorrect name for starting level set preset."
              )
      else:
          res = init_level_set
      return res.astype(dtype, copy=False)
  
file_path: scikit-image/skimage/segmentation/_chan_vese.py
imports: import numpy
  from scipy.ndimage import distance_transform_edt
  from .._shared.utils import _supported_float_type
label_desc: Use image node_id 12 for calling a global function with example usage: _cv_init_level_set(init_level_set, image_shape, dtype) and returns: res