code: def _unique_indicator(y):
      return np.arange(check_array(y, ["csr", "csc", "coo"]).shape[1])
  
imports: from __future__ import division
  from collections import Sequence
  from itertools import chain
  from scipy.sparse import issparse
  from scipy.sparse.base import spmatrix
  from scipy.sparse import dok_matrix
  from scipy.sparse import lil_matrix
  import numpy
  from ..externals.six import string_types
  from .validation import check_array
  from ..utils.fixes import bincount
  from ..utils.fixes import array_equal
label_desc: Use image node_id 2 for calling a global function with example usage: _unique_indicator(y) and returns: np