def recall_checksum(self, cache_file):
        """
        Get the checksum of the input used to generate a binary distribution archive.

        :param cache_file: The pathname of the binary distribution archive (a string).
        :returns: The checksum (a string) or :data:`None` (when no checksum is available).
        """
        # EAFP instead of LBYL because of concurrency between pip-accel
        # processes (https://docs.python.org/2/glossary.html#term-lbyl).
        checksum_file = '%s.txt' % cache_file
        try:
            with open(checksum_file) as handle:
                contents = handle.read()
            return contents.strip()
        except IOError as e:
            if e.errno == errno.ENOENT:
                # Gracefully handle missing checksum files.
                return None
            else:
                # Don't swallow exceptions we don't expect!
                raise
def recall_checksum ( self , cache_file ) : checksum_file = '%s.txt' % cache_file try : with open ( checksum_file ) as handle : contents = handle . read ( ) return contents . strip ( ) except IOError as e : if e . errno == errno . ENOENT : return None else : raise
Get the checksum of the input used to generate a binary distribution archive.

        :param cache_file: The pathname of the binary distribution archive (a string).
        :returns: The checksum (a string) or :data:`None` (when no checksum is available).