code: def _unwindk(z):
      """
      Compute the scalar unwinding number.
  
      Uses Eq. (5.3) in [1]_, and should be equal to (z - log(exp(z)) / (2 pi i).
      Note that this definition differs in sign from the original definition
      in equations (5, 6) in [2]_.  The sign convention is justified in [3]_.
  
      Parameters
      ----------
      z : complex
          A complex number.
  
      Returns
      -------
      unwinding_number : integer
          The scalar unwinding number of z.
  
      References
      ----------
      .. [1] Nicholas J. Higham and Lijing lin (2011)
             "A Schur-Pade Algorithm for Fractional Powers of a Matrix."
             SIAM Journal on Matrix Analysis and Applications,
             32 (3). pp. 1056-1078. ISSN 0895-4798
  
      .. [2] Robert M. Corless and David J. Jeffrey,
             "The unwinding number." Newsletter ACM SIGSAM Bulletin
             Volume 30, Issue 2, June 1996, Pages 28-35.
  
      .. [3] Russell Bradford and Robert M. Corless and James H. Davenport and
             David J. Jeffrey and Stephen M. Watt,
             "Reasoning about the elementary functions of complex analysis"
             Annals of Mathematics and Artificial Intelligence,
             36: 303-318, 2002.
  
      """
      return int(np.ceil((z.imag - np.pi) / (2 * np.pi)))
  
imports: from __future__ import division, print_function, absolute_import
  import warnings
  import numpy
  from scipy.linalg._matfuncs_sqrtm import SqrtmError, _sqrtm_triu
  from scipy.linalg.decomp_schur import schur, rsf2csf
  from scipy.linalg.matfuncs import funm
  from scipy.linalg import svdvals, solve_triangular
  from scipy.sparse.linalg.interface import LinearOperator
  from scipy.sparse.linalg import onenormest
  import scipy.special
label_desc: Use image node_id 2 for calling a global function with example usage: _unwindk(z) and returns: int