code: def csr_vstack(a, b) -> DatasetLike:
      """Takes in 2 csr_matrices and appends the second one to the bottom of the first one.
      Alternative to scipy.sparse.vstack. Returns a sparse matrix.
      """
      a.data = np.hstack((a.data, b.data))
      a.indices = np.hstack((a.indices, b.indices))
      a.indptr = np.hstack((a.indptr, (b.indptr + a.nnz)[1:]))
      a._shape = (a.shape[0] + b.shape[0], b.shape[1])
      return a
  
imports: import warnings
  import numpy
  import pandas
  from typing import Union, Tuple
  from cleanlab.typing import DatasetLike, LabelLike
  from cleanlab.internal.validation import labels_to_array
  from cleanlab.internal.constants import FLOATING_POINT_COMPARISON, TINY_VALUE
label_desc: Use image node_id 24 for calling a global function with example usage: csr_vstack(a, b) and returns: a