code: def __init__(self, group, name=""):
      # self.group = np.asarray(group)  # TODO: use checks in combine_indices
      self.name = name
      uni, uni_idx, uni_inv = combine_indices(group)
  
      # TODO: rename these to something easier to remember
      self.group_int, self.uni_idx, self.uni = uni, uni_idx, uni_inv
  
      self.n_groups = len(self.uni)
  
      # put this here so they can be overwritten before calling labels
      self.separator = "."
      self.prefix = self.name
      if self.prefix:
          self.prefix = self.prefix + "="
  
imports: from statsmodels.compat.python import lrange, lzip
  import numpy
  import pandas
  import statsmodels.tools.data
  from pandas import Index, MultiIndex
label_desc: Use image node_id 1 to create a new Group object  with example: obj = Group(group, name)