rem: tabs = TRUE;
add: tabs = true;
context: get_space (FILE *f, register int c){  for (;;)    {      if (c == ' ')	in_column++;      else if (c == '\t')	{	  tabs = TRUE;	  in_column = (in_column / TABWIDTH + 1) * TABWIDTH;	}      else	return c;      c = getc (f);    }}