Validate the input

def check_required(config):
    """Validate the input"""
    if config.get('domain_key') is None:
        raise CfgError("The domain_key option is required")
    if config.get('remote_loc') is None:
        raise CfgError("The remote_location option is required")
    if config.get('gpg_keyid') is None:
        raise CfgError("The gpg_keyid option is required")