code: def _trace(A):
      # A compatibility function which should eventually disappear.
      if scipy.sparse.isspmatrix(A):
          return A.diagonal().sum()
      elif is_pydata_spmatrix(A):
          return A.to_scipy_sparse().diagonal().sum()
      else:
          return np.trace(A)
  
imports: import numpy
  import scipy.linalg
  import scipy.sparse.linalg
  from scipy.sparse.linalg import aslinearoperator
  from scipy.sparse.sputils import is_pydata_spmatrix
label_desc: Use image node_id 3 for calling a global function with example usage: _trace(A) and returns: A, A, np