Add 'Users' type to generator

pkg/generator/base.go

@@ -0,0 +1,14 @@
+package generator
+
+import "github.com/aykhans/bsky-feedgen/pkg/utils"
+
+type Users map[string]bool
+
+func (u Users) IsValid(did string) *bool {
+	isValid, ok := u[did]
+	if ok == false {
+		return nil
+	}
+
+	return utils.ToPtr(isValid)
+}