text: #!/usr/bin/env python
  # coding: utf-8
  #
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  #  in the Software without restriction, including without limitation the rights
  #  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  #  copies of the Software, and to permit persons to whom the Software is
  #  furnished to do so, subject to the following conditions:
  #  .
  #  The above copyright notice and this permission notice shall be included in
  #  all copies or substantial portions of the Software.
  #  .
  #  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  #  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  #  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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  #  THE SOFTWARE.
  """Unique place where the version number is defined.
  
  provides:
  * version = "1.2.3" or "1.2.3-beta4"
  * version_info = named tuple (1,2,3,"beta",4)
  * hexversion: 0x010203B4
  * strictversion = "1.2.3b4
  * debianversion = "1.2.3~beta4"
  * calc_hexversion: the function to transform a version_tuple into an integer
  
  This is called hexversion since it only really looks meaningful when viewed as the
  result of passing it to the built-in hex() function.
  The version_info value may be used for a more human-friendly encoding of the same information.
  
  The hexversion is a 32-bit number with the following layout:
  Bits (big endian order)     Meaning
  1-8     PY_MAJOR_VERSION (the 2 in 2.1.0a3)
  9-16     PY_MINOR_VERSION (the 1 in 2.1.0a3)
  17-24     PY_MICRO_VERSION (the 0 in 2.1.0a3)
  25-28     PY_RELEASE_LEVEL (0xA for alpha, 0xB for beta, 0xC for release candidate and 0xF for final)
  29-32     PY_RELEASE_SERIAL (the 3 in 2.1.0a3, zero for final releases)
  
  Thus 2.1.0a3 is hexversion 0x020100a3.
  
  """
  
  __authors__ = ["Jérôme Kieffer", "V. Valls"]
  __license__ = "MIT"
  __copyright__ = "European Synchrotron Radiation Facility, Grenoble, France"
  __date__ = "21/01/2021"
  __status__ = "production"
  __docformat__ = 'restructuredtext'
  __all__ = ["date", "version_info", "strictversion", "hexversion", "debianversion",
             "calc_hexversion", "citation"]
  
  RELEASE_LEVEL_VALUE = {"dev": 0,
                         "alpha": 10,
                         "beta": 11,
                         "gamma": 12,
                         "rc": 13,
                         "final": 15}
  
  MAJOR = 0
  MINOR = 21
  MICRO = 0
  RELEV = "dev"  # <16
  SERIAL = 0  # <16
  
  date = __date__
  
  from collections import namedtuple
  _version_info = namedtuple("version_info", ["major", "minor", "micro", "releaselevel", "serial"])
  
  version_info = _version_info(MAJOR, MINOR, MICRO, RELEV, SERIAL)
  
  strictversion = version = debianversion = "%d.%d.%d" % version_info[:3]
  if version_info.releaselevel != "final":
      version += "-%s%s" % version_info[-2:]
      debianversion += "~adev%i" % version_info[-1] if RELEV == "dev" else "~%s%i" % version_info[-2:]
      prerel = "a" if RELEASE_LEVEL_VALUE.get(version_info[3], 0) < 10 else "b"
      if prerel not in "ab":
          prerel = "a"
      strictversion += prerel + str(version_info[-1])
  
  _PATTERN = None
  
  
  def calc_hexversion(major=0, minor=0, micro=0, releaselevel="dev", serial=0, string=None):
      """Calculate the hexadecimal version number from the tuple version_info:
  
      :param major: integer
      :param minor: integer
      :param micro: integer
      :param relev: integer or string
      :param serial: integer
      :param string: version number as a string
      :return: integer always increasing with revision numbers
      """
      if string is not None:
          global _PATTERN
          if _PATTERN is None:
              import re
              _PATTERN = re.compile(r"(\d+)\.(\d+)\.(\d+)(\w+)?$")
          result = _PATTERN.match(string)
          if result is None:
              raise ValueError("'%s' is not a valid version" % string)
          result = result.groups()
          major, minor, micro = int(result[0]), int(result[1]), int(result[2])
          releaselevel = result[3]
          if releaselevel is None:
              releaselevel = 0
  
      try:
          releaselevel = int(releaselevel)
      except ValueError:
          releaselevel = RELEASE_LEVEL_VALUE.get(releaselevel, 0)
  
      hex_version = int(serial)
      hex_version |= releaselevel * 1 << 4
      hex_version |= int(micro) * 1 << 8
      hex_version |= int(minor) * 1 << 16
      hex_version |= int(major) * 1 << 24
      return hex_version
  
  
  hexversion = calc_hexversion(*version_info)
  
  citation = "doi:10.1107/S1600576715004306"
  
  if __name__ == "__main__":
      print(version)
  