def load_credentials(self, profile="default"):
        f = profile_path(DBPY_PROFILE_ID, profile)
        if f:
            creds = load_from_json(f)
            self.username = creds.get('username')
            self.password = creds.get('password')
            self.hostname = creds.get('hostname')
            self.port = creds.get('port')
            self.filename = creds.get('filename')
            self.dbname = creds.get('dbname')
            self.dbtype = creds.get('dbtype')
            self.schemas = creds.get('schemas')
            self.limit = creds.get('limit')
            self.keys_per_column = creds.get('keys_per_column')
        else:
            raise Exception("Credentials not configured!")
Loads crentials for a given profile. Profiles are stored in
dataset/ETHPy150Open yhat/db.py/db/db.py/DB.load_credentials