func DefaultFromEnv(attr NamedAttr, checker schema.Checker) (val interface{}, _ string, err error) {
	val, envVar := defaultFromEnv(attr)
	if val == "" {
		return nil, "", nil
	}
	v, err := checker.Coerce(val, nil)
	if err != nil {
		return nil, "", errgo.Notef(err, "cannot convert $%s", envVar)
	}
	return v, "", nil
}
// DefaultFromEnv returns any default value found in the environment for
// the given attribute.
//
// The environment variables specified in attr will be checked in order
// and the first non-empty value found is coerced using the given
// checker and returned.
DefaultFromEnv returns any default value found in the environment for
the given attribute.

The environment variables specified in attr will be checked in order
and the first non-empty value found is coerced using the given
checker and returned.
// DefaultFromEnv returns any default value found in the environment for // the given attribute . // // The environment variables specified in attr will be checked in order // and the first non - empty value found is coerced using the given // checker and returned .
func DefaultFromEnv(attr NamedAttr, checker schema.Checker) (val interface{}, _ string, err error) {
	val, envVar := defaultFromEnv(attr)
	if val == "" {
		return nil, "", nil
	}
	v, err := checker.Coerce(val, nil)
	if err != nil {
		return nil, "", errgo.Notef(err, "cannot convert $%s", envVar)
	}
	return v, "", nil
}
func DefaultFromEnv ( attr NamedAttr , checker schema . Checker ) ( val interface { } , _ string , err error ) { val , envVar := defaultFromEnv ( attr ) if val == " " { return nil , " " , nil } v , err := checker . Coerce ( val , nil ) if err != nil { return nil , " " , errgo . Notef ( err , " " , envVar ) } return v , " " , nil }
DefaultFromEnv returns any default value found in the environment for
the given attribute.
DefaultFromEnv returns any default value found in the environment for the given attribute .