Index: src/natools-s_expressions-interpreters.adb
==================================================================
--- src/natools-s_expressions-interpreters.adb
+++ src/natools-s_expressions-interpreters.adb
@@ -39,10 +39,22 @@
    begin
       Self.Commands.Insert (Name, Cmd);
       Self.Max_Length := Count'Max (Self.Max_Length, Name'Length);
    end Add_Command;
 
+
+   function Has_Command (Self : Interpreter; Name : Atom) return Boolean is
+   begin
+      return Self.Commands.Contains (Name);
+   end Has_Command;
+
+
+   function Is_Empty (Self : Interpreter) return Boolean is
+   begin
+      return Self.Commands.Is_Empty;
+   end Is_Empty;
+
 
    procedure Set_Fallback
      (Self : in out Interpreter;
       Name : in Atom)
    is

Index: src/natools-s_expressions-interpreters.ads
==================================================================
--- src/natools-s_expressions-interpreters.ads
+++ src/natools-s_expressions-interpreters.ads
@@ -63,10 +63,14 @@
 
    procedure Add_Command
      (Self : in out Interpreter;
       Name : in Atom;
       Cmd : in Command'Class);
+
+   function Has_Command (Self : Interpreter; Name : Atom) return Boolean;
+
+   function Is_Empty (Self : Interpreter) return Boolean;
 
    procedure Set_Fallback
      (Self : in out Interpreter;
       Name : in Atom);