code: def determine_version(self, request, api_version=None):
          
          if api_version is False:
              api_version = None
              for version in self.versions:
                  if version and "v{0}".format(version) in request.path:
                      api_version = version
                      break
  
          request_version = set()
          if api_version is not None:
              request_version.add(api_version)
  
          version_header = request.get_header("X-API-VERSION")
          if version_header:
              request_version.add(version_header)
  
          version_param = request.get_param('api_version')
          if version_param is not None:
              request_version.add(version_param)
  
          if len(request_version) > 1:
              raise ValueError('You are requesting conflicting versions')
  
          return next(iter(request_version or (None, )))
docs: Determines the appropriate version given the set api_version, the request header, and URL query params