code: def baseTargetSpec(self):
          ''' returns pack.DependencySpec for the base target of this target (or
              None if this target does not inherit from another target.
          '''
          inherits = self.description.get('inherits', {})
          if len(inherits) == 1:
              name, version_req = list(inherits.items())[0]
              shrinkwrap_version_req = self.getShrinkwrapMapping('targets').get(name, None)
              if shrinkwrap_version_req is not None:
                  logger.debug(
                      'respecting shrinkwrap version %s for %s', shrinkwrap_version_req, name
                  )
              return pack.DependencySpec(
                  name,
                  version_req,
                  shrinkwrap_version_req = shrinkwrap_version_req
              )
          elif len(inherits) > 1:
              logger.error('target %s specifies multiple base targets, but only one is allowed', self.getName())
          return Nonf baseTargetSpec(self):
          ''' returns pack.DependencySpec for the base target of this target (or
              None if this target does not inherit from another target.
          '''
          inherits = self.description.get('inherits', {})
          if len(inherits) == 1:
              name, version_req = list(inherits.items())[0]
              shrinkwrap_version_req = self.getShrinkwrapMapping('targets').get(name, None)
              if shrinkwrap_version_req is not None:
                  logger.debug(
                      'respecting shrinkwrap version %s for %s', shrinkwrap_version_req, name
                  )
              return pack.DependencySpec(
                  name,
                  version_req,
                  shrinkwrap_version_req = shrinkwrap_version_req
              )
          elif len(inherits) > 1:
              logger.error('target %s specifies multiple base targets, but only one is allowed', self.getName())
          return None
docs: returns pack.DependencySpec for the base target of this target (or
              None if this target does not inherit from another target.