'Given a block_dict return all the asset_ids for that block (the txid
of CREATE transactions). Useful to know which assets to retrieve
from the database to reconstruct the block.
Args:
block_dict (:obj:`dict`): The block dict as returned from a
database call.
Returns:
list: The list of asset_ids in the block.'

@staticmethod
def get_asset_ids(block_dict):

    asset_ids = []
    for transaction in block_dict['block']['transactions']:
        if (transaction['operation'] in [Transaction.CREATE, Transaction.GENESIS]):
            asset_ids.append(transaction['id'])
    return asset_ids
