code: def b0_threshold_update_slicing_message(slice_start):
      """Message for b0 threshold value update for slicing.
  
      Parameters
      ----------
      slice_start : int
          Starting index for slicing.
  
      Returns
      -------
      str
          Message.
      """
  
      return f"Updating b0_threshold to {slice_start} for slicing."
  
imports: import logging
  from warnings import warn
  import numpy
  from scipy.linalg import inv, polar
  from dipy.io import gradients
  from dipy.core.onetime import auto_attr
  from dipy.core.geometry import vector_norm, vec2vec_rotmat
  from dipy.core.sphere import disperse_charges, HemiSphere
  from dipy.utils.deprecator import deprecate_with_version
label_desc: Use image node_id 3 for calling a global function with example usage: b0_threshold_update_slicing_message(slice_start) and returns: str, slice_start, str