diff --git a/pkg/obiseq/language.go b/pkg/obiseq/language.go
index 0f3f61c..b0abaf6 100644
--- a/pkg/obiseq/language.go
+++ b/pkg/obiseq/language.go
@@ -3,6 +3,7 @@ package obiseq
 import (
 	"fmt"
 	"log"
+	"reflect"
 	"strings"
 
 	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obiutils"
@@ -139,6 +140,13 @@ var OBILang = gval.NewLanguage(
 		length := obiutils.Len(args[0])
 		return (float64)(length), nil
 	}),
+	gval.Function("contains", func(args ...interface{}) (interface{}, error) {
+		if obiutils.IsAMap(args[0]) {
+			val := reflect.ValueOf(args[0]).MapIndex(reflect.ValueOf(args[1]))
+			return val.IsValid(), nil
+		}
+		return false, nil
+	}),
 	gval.Function("ismap", func(args ...interface{}) (interface{}, error) {
 		ismap := obiutils.IsAMap(args[0])
 		return ismap, nil