rb_io_check_writable  916 ext/openssl/ossl_ssl.c         rb_io_check_writable(fptr);
rb_io_check_writable  147 include/ruby/io.h void rb_io_check_writable(rb_io_t*);
rb_io_check_writable  912 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 1919 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 3509 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 7738 io.c                   rb_io_check_writable(dst_fptr);