code: def pad(mat, padrow, padcol):
      """Add additional rows/columns to `mat`. The new rows/columns will be initialized with zeros.
  
      Parameters
      ----------
      mat : numpy.ndarray
          Input 2D matrix
      padrow : int
          Number of additional rows
      padcol : int
          Number of additional columns
  
      Returns
      -------
      numpy.matrixlib.defmatrix.matrix
          Matrix with needed padding.
  
      """
      if padrow < 0:
          padrow = 0
      if padcol < 0:
          padcol = 0
      rows, cols = mat.shape
      return np.block(
          [
              [mat, np.zeros((rows, padcol))],
              [np.zeros((padrow, cols + padcol))],
          ]
      )
  
imports: from __future__ import with_statement
  import logging
  import math
  from gensim import utils
  import numpy
  import scipy.sparse
  from scipy.stats import entropy
  from scipy.linalg import get_blas_funcs, triu
  from scipy.linalg.lapack import get_lapack_funcs
  from scipy.special import psi
label_desc: Use image node_id 4 for calling a global function with example usage: pad(mat, padrow, padcol) and returns: np