code: def _fac2(n):
      """Compute the double factorial of an integer.
  
      The function uses the definition :math:`(-1)!! = 1`.
  
      Args:
          n (int): number for which the double factorial is computed
  
      Returns:
          int: the computed double factorial
  
      """
      return int(fac2(n) if n != -1 else 1)
  
imports: import itertools
  import numpy
  from scipy.special import factorial2
  import pennylane
label_desc: Use image node_id 3 for calling a global function with example usage: _fac2(n) and returns: int