rb_econv_prepare_opts 3447 ext/zlib/zlib.c 	gz->ecflags = rb_econv_prepare_opts(opts, &opts);
rb_econv_prepare_opts  306 include/ruby/encoding.h int rb_econv_prepare_opts(VALUE opthash, VALUE *ecopts);
rb_econv_prepare_opts 2760 transcode.c    	ecflags = rb_econv_prepare_opts(opt, &ecopts);
rb_econv_prepare_opts 3019 transcode.c            ecflags = rb_econv_prepare_opts(opt, &ecopts);