code: def generate_checksum(did, metadata):
          
          files_checksum = ''
          for file in metadata['base']['files']:
              if 'checksum' in file:
                  files_checksum = files_checksum + file['checksum']
          return hashlib.sha3_256((files_checksum +
                                   metadata['base']['name'] +
                                   metadata['base']['author'] +
                                   metadata['base']['license'] +
                                   did).encode('UTF-8')).hexdigest()
docs: Generation of the hash for integrity checksum.
  
          :param did: DID, str
          :param metadata: conforming to the Metadata accepted by Ocean Protocol, dict
          :return: hex str