### SUMMARY
```
  sha256sum:
    description:
      - If a SHA-256 checksum is passed to this parameter, the digest of the
        destination file will be calculated after it is downloaded to ensure
        its integrity and verify that the transfer completed successfully.
        This option is deprecated. Use C(checksum) instead.
```

There is no `module.deprecate` either for `sha256sum`.

the argument has been declared deprecated in commit b3b11fbce26 (2017)

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
get_url

* ansible version: 2.10

checksum = 'sha256:%s' % (sha256sum)
    
    if checksum:
        try:
            algorithm, checksum = checksum.split(':', 1)
        except ValueError:
            module.fail_json(msg="The checksum parameter has to be in format <algorithm>:<checksum>", **result)
        if checksum.startswith('http://') or checksum.startswith('https://') or checksum.startswith('ftp://'):
            checksum_url = checksum
            
            checksum_tmpsrc, checksum_info = url_get(module, checksum_url, dest, use_proxy, last_mod_time, force, timeout, headers, tmp_dest)
            with open(checksum_tmpsrc) as f:
                lines = [line.rstrip('\n') for line in f]
            os.remove(checksum_tmpsrc)
            checksum_map = {}
            for line in lines:
                parts = line.split(None, 1)
                if len(parts) == 2:
                    checksum_map[parts[0]] = parts[1]
            filename = url_filename(url)
            
            
            for cksum in (s for (s, f) in checksum_map.items() if f.strip('./') == filename):
                checksum = cksum
                break
            else:
                checksum = None
            if checksum is None:
                module.fail_json(msg="Unable to find a checksum for file '%s' in '%s'" % (filename, checksum_url))