code: def get(self, filename):
          
          pathname = os.path.join(self.config.binary_cache, filename)
          if os.path.isfile(pathname):
              logger.debug("Distribution archive exists in local cache (%s).", pathname)
              return pathname
          else:
              logger.debug("Distribution archive doesn't exist in local cache (%s).", pathname)
              return None
docs: Check if a distribution archive exists in the local cache.
  
          :param filename: The filename of the distribution archive (a string).
          :returns: The pathname of a distribution archive on the local file
                    system or :data:`None`.