code: def diagonal(self, k=0):
      rows, cols = self.shape
      if k <= -rows or k >= cols:
          return np.empty(0, dtype=self.data.dtype)
      (idx,) = np.nonzero(self.offsets == k)
      first_col = max(0, k)
      last_col = min(rows + k, cols)
      result_size = last_col - first_col
      if idx.size == 0:
          return np.zeros(result_size, dtype=self.data.dtype)
      result = self.data[idx[0], first_col:last_col]
      padding = result_size - len(result)
      if padding > 0:
          result = np.pad(result, (0, padding), mode="constant")
      return result
  
imports: import numpy
  from ._matrix import spmatrix
  from ._base import issparse, _formats, _spbase, sparray
  from ._data import _data_matrix
  from ._sputils import isshape, upcast_char, getdtype, get_sum_dtype, validateaxis, check_shape
  from ._sparsetools import dia_matvec
label_desc: Use image node_id 13 for calling the _dia_base obj's underlying member method code with example usage: obj.diagonal(k) and returns: result, np, np