code: def _extend(M, sym):
      """Extend window by 1 sample if needed for DFT-even symmetry"""
      if not sym:
          return M + 1, True
      else:
          return M, False
  
imports: from __future__ import division, print_function, absolute_import
  import operator
  import warnings
  import numpy
  from scipy import fftpack, linalg, special
  from scipy._lib.six import string_types
label_desc: Use image node_id 2 for calling a global function with example usage: _extend(M, sym) and returns: unknown,  True, M,  False