using constants for flags

Signed-off-by: metonymic-smokey <ahuja.aditi@gmail.com>

cmd/thanos/query.go

@@ -52,6 +52,11 @@ import (
 	"github.com/thanos-io/thanos/pkg/ui"
 )
 
+const (
+	promqlNegativeOffset = "promql-negative-offset"
+	promqlAtModifier     = "promql-at-modifier"
+)
+
 // registerQuery registers a query command.
 func registerQuery(app *extkingpin.App) {
 	comp := component.Query
@@ -146,7 +151,7 @@ func registerQuery(app *extkingpin.App) {
 	enableMetricMetadataPartialResponse := cmd.Flag("metric-metadata.partial-response", "Enable partial response for metric metadata endpoint. --no-metric-metadata.partial-response for disabling.").
 		Hidden().Default("true").Bool()
 
-	featureList := cmd.Flag("enable-feature", "Comma separated experimental feature names to enable.The current list of features is promql-negative-offset and promql-at-modifier.").Default("").Strings()
+	featureList := cmd.Flag("enable-feature", "Comma separated experimental feature names to enable.The current list of features is "+promqlNegativeOffset+" and "+promqlAtModifier+".").Default("").Strings()
 
 	enableExemplarPartialResponse := cmd.Flag("exemplar.partial-response", "Enable partial response for exemplar endpoint. --no-exemplar.partial-response for disabling.").
 		Hidden().Default("true").Bool()
@@ -167,10 +172,10 @@ func registerQuery(app *extkingpin.App) {
 
 		var enableNegativeOffset, enableAtModifier bool
 		for _, feature := range *featureList {
-			if feature == "promql-negative-offset" {
+			if feature == promqlNegativeOffset {
 				enableNegativeOffset = true
 			}
-			if feature == "promql-at-modifier" {
+			if feature == promqlAtModifier {
 				enableAtModifier = true
 			}
 		}