rb_fd_clr         213 include/ruby/intern.h void rb_fd_clr(int, rb_fdset_t *);
rb_fd_clr        2249 thread.c       #define FD_CLR(i, f)	rb_fd_clr(i, f)
rb_fd_clr        2295 thread.c       #define FD_CLR(i, f)	rb_fd_clr(i, f)