def METHOD_NAME(Self, append):
    config_relative_path = "configuration"
    config_path = os.path.join(os.getcwd(), config_relative_path)
    if not append:
        Self.configuration_values = []
    for file in Self.configuration_files:
        try:
            file_string = open(os.path.join(config_path, file), "r").read()
            file_lines = file_string.split("\n")
            for line in file_lines:
                start = line.find("(")
                end = line.find(")")
                if (start > -1) & (end > 0) & (line.find("SCRIPT") == -1):
                    Self.configuration_values.append(line[start + 1 : end])
        except OSError:
            print("Could not open/read file:", config_path)
            sys.exit()
    Self.configuration_values = list(dict.fromkeys(Self.configuration_values))