/// <summary>
        ///
        /// </summary>
        /// <param name="varBuilder"></param>
        internal void RemoveVarMap(VariableMapBuilder varBuilder)
        {
            var rv = _requiredVars.SingleOrDefault(v => v.VarName == varBuilder.VarName);

            if (rv != null)
            {
                _requiredVars.Remove(rv);
            }
        }
 /// <summary>
 ///
 /// </summary>
 /// <param name="varBuilder"></param>
 internal void AddReplaceVarMap(VariableMapBuilder varBuilder)
 {
     RemoveVarMap(varBuilder);
     _requiredVars.Add(varBuilder);
 }