code: def _init_mat(nrows, ncols, ins_cost, del_cost):
      mat = np.empty((nrows, ncols))
      mat[0, :] = ins_cost * np.arange(ncols)
      mat[:, 0] = del_cost * np.arange(nrows)
      return mat
  
label_desc: Use image node_id 2 for calling a global function with example usage: _init_mat(nrows, ncols, ins_cost, del_cost) and returns: mat