def validate_setting(module, setting, param):
    """Checks if a Compass setting exists in the config file.

    :param module   : module name to be checked
    :type module    : string
    :param setting  : compass setting wrapper
    :type setting   : python module
    :param param    : settings defined in compass config file
    :type param     : string

    """
    if hasattr(setting, param):
        return True
    else:
        err_msg = "[%s]Error: no %s defined" % (module, param)
        return err_msg