code: def prepare_2dgrid(hist):
      """Get lists of all unique x and y keys
  
      Used as input by get_2dgrid(hist).
  
      :param hist: input histogrammar histogram
      :return: two sorted lists of unique x and y keys
      """
      return prepare_ndgrid(hist, n_dim=2)
  
imports: from __future__ import annotations
  import warnings
  import histogrammar
  import numpy
  from histogrammar.util import get_hist_props
  from popmon.hist.hist_utils import get_bin_centers, is_numeric
  from popmon.stats.numpy import quantile
label_desc: Use image node_id 2 for calling a global function with example usage: prepare_2dgrid(hist) and returns: prepare_ndgrid