bstart:		'{'	{
			PushInt(NumSymbols(v_table));
			PushInt(NumSymbols(t_table));
			PushInt(NumSymbols(p_table));
			}
		;

bend:		'}'	{
			int n;

			n = NumSymbols(p_table) - PopInt();
			if (n>0) PopSymbols(p_table,n);

			n = NumSymbols(t_table) - PopInt();
			if (n>0) PopSymbols(t_table,n);

			n = NumSymbols(v_table) - PopInt();
			if (n>0) PopSymbols(v_table,n);
			}
		;
