def to_ok(val, default_value='[OK]', ok_values=nil, error_values=[nil, false])
      return '[OK]' if ok_values && ok_values.include?(val)
      return '[ERROR]' if error_values && error_values.include?(val)
      return default_value
    end
def to_ok(val, default_value='[OK]', ok_values=nil, error_values=[nil, false])
      return '[OK]' if ok_values && ok_values.include?(val)
      return '[ERROR]' if error_values && error_values.include?(val)
      return default_value
    end
Map given value to [OK] or [ERROR]
 By default return [OK] unless value is false or nil
 Override default behavior by using 'ok_values' and/or 'error_values'

 === Parameters
 val(Object):: Value to be tested
 default_ok(Boolean):: Whether default value is '[OK]' (true) or '[ERROR]' (false), '[OK]' by default
 ok_values(Array):: Array of values that will cause +to_ok+ to return '[OK]' if defined, nil by default
 error_values(Array):: Array of values that will cause +to_ok+ to return '[ERROR]' if defined, [nil, false] by default

 === Return
 status(String):: [OK] or [ERROR]