code: def file_hash(path, hash_type='md5'):
      
      if os.path.exists(path):
          h = getattr(hashlib, hash_type)()
          with open(path, 'rb') as source:
              h.update(source.read())
          return h.hexdigest()
      else:
          return None
docs: Generate a hash checksum of the contents of 'path' or None if not found.
  
      :param str hash_type: Any hash alrgorithm supported by :mod:`hashlib`,
                            such as md5, sha1, sha256, sha512, etc.