class_docstr: Vectorized slice/HARM sampler.
  
  Can revert until all previous steps have likelihoods allL above Lmin.
  Updates currentt, generation and allL, in-place.
docstr: Pick starting direction and range for slice.
  
  Parameters
  ----------
  region: MLFriends object
      Region
  mask_starting: np.array(nwalkers, dtype=bool)
      which walkers to set up.
docstr_tok: ["Pick","starting","direction","and","range","for","slice",".","Parameters","--","--","--","--","--","region",":","MLFriends","object","Region","mask_starting",":","np.array","(","nwalkers",",","dtype=bool",")","which","walkers","to","set","up","."]
code: def setup_brackets(self, mask_starting, region):
      """Pick starting direction and range for slice.
  
      Parameters
      ----------
      region: MLFriends object
          Region
      mask_starting: np.array(nwalkers, dtype=bool)
          which walkers to set up.
  
      """
      if self.log:
          print("starting brackets:", mask_starting)
      (i_starting,) = np.where(mask_starting)
      self.current_left[i_starting] = -self.scale
      self.current_right[i_starting] = self.scale
      self.searching_left[i_starting] = True
      self.searching_right[i_starting] = True
      self.currentt[i_starting] = 0
      # choose direction for new slice
      self.currentv[i_starting, :] = self.generate_direction(
          self.allu[i_starting, self.generation[i_starting]], region
      )
  
imports: import numpy
  from ultranest.utils import submasks
  from ultranest.stepfuncs import evolve, step_back
  from ultranest.stepfuncs import generate_cube_oriented_direction, generate_cube_oriented_direction_scaled
  from ultranest.stepfuncs import generate_random_direction, generate_region_oriented_direction, generate_region_random_direction
  from ultranest.stepfuncs import generate_differential_direction, generate_mixture_random_direction
  import scipy.stats
label_desc: Use image node_id 7 for calling the PopulationSliceSampler obj's underlying member method code with example usage: obj.setup_brackets(mask_starting, region) without return types