parameters: (num, den)
return_statement: return num, den
docstring: Change a transfer function from the variable `z` to `z**-1`.
  
          Parameters
          ----------
          num, den: 1d array_like
              Sequences representing the coefficients of the numerator and
              denominator polynomials, in order of ascending degree of 'z**-1'.
              That is, ``5 + 3 z**-1 + 2 z**-2`` is presented as ``[5, 3, 2]``.
  
          Returns
          -------
          num, den: 1d array_like
              Sequences representing the coefficients of the numerator and
              denominator polynomials, in order of descending degree of 'z'.
              That is, ``5z**2 + 3z + 2`` is presented as ``[5, 3, 2]``.
docstring_summary: Change a transfer function from the variable `z` to `z**-1`.
docstring_tokens: Change a transfer function from the variable z to z ** - 1 .
function: def _zinv_to_z(num, den):
          """Change a transfer function from the variable `z` to `z**-1`.
  
          Parameters
          ----------
          num, den: 1d array_like
              Sequences representing the coefficients of the numerator and
              denominator polynomials, in order of ascending degree of 'z**-1'.
              That is, ``5 + 3 z**-1 + 2 z**-2`` is presented as ``[5, 3, 2]``.
  
          Returns
          -------
          num, den: 1d array_like
              Sequences representing the coefficients of the numerator and
              denominator polynomials, in order of descending degree of 'z'.
              That is, ``5z**2 + 3z + 2`` is presented as ``[5, 3, 2]``.
          """
          diff = len(num) - len(den)
          if diff > 0:
              den = np.hstack((den, np.zeros(diff)))
          elif diff < 0:
              num = np.hstack((num, np.zeros(-diff)))
          return num, den
function_tokens: def _zinv_to_z ( num , den ) : diff = len ( num ) - len ( den ) if diff > 0 : den = np . hstack ( ( den , np . zeros ( diff ) ) ) elif diff < 0 : num = np . hstack ( ( num , np . zeros ( - diff ) ) ) return num , den