def METHOD_NAME(self, wallet_file):
    """Gets birthheight of a wallet on node0"""
    with open(os.path.join(self.nodes[0].datadir, wallet_file), 'r', encoding="utf8") as f:
        for line in f:
            if line.startswith('# * Best block at time of backup'):
                wallet_birthheight = int(line.split(' ')[9])
                return wallet_birthheight