code: def ismatrix(t):
      return (
          isinstance(t, (list, tuple))
          and len(t) > 0
          and issequence(t[0])
      ) or (isinstance(t, np.ndarray) and t.ndim == 2)
  
imports: from __future__ import division, print_function, absolute_import
  import operator
  import warnings
  import numpy
  from scipy._lib._version import NumpyVersion
label_desc: Use image node_id 13 for calling a global function with example usage: ismatrix(t) and returns: unknown