code: def fingerprint_file(workspace, filename):
    
    content = read_file(os.path.join(workspace, filename), binary_mode=True)
    fingerprint = hashlib.sha256(content)
    b64_encoded = base64.b64encode(fingerprint.digest())
    return 'sha256={}'.format(b64_encoded.decode('utf-8')), str(len(content))
docs: Given a relative filename located in a workspace, fingerprint the file.
  
    Returns a tuple of fingerprint string and size string.