def get_flag(var, fallback, expected=True, warn=True):<EOL>
val = get_config_var(var)<EOL>if val is None:<EOL><INDENT>if warn:<EOL><INDENT>logger.debug("<STR_LIT>"<EOL>"<STR_LIT>", var)<EOL><DEDENT>return fallback()<EOL><DEDENT>return val == expected<EOL>
Use a fallback method for determining SOABI flags if the needed config
    var is unset or unavailable.