function scr_84_pop() { if (!variable_global_exists("chemg_stack")) { global.chemg_stack = array_create(0); global.chemg_stack[0] = 0; } var top_ndx = global.chemg_stack[0]; if (top_ndx <= 0) show_error("stack empty", true); global.chemg_stack[0] = top_ndx - 1; return global.chemg_stack[top_ndx]; }