End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

instance method

IO#to_io

to_io → self

static VALUE
rb_io_to_io(VALUE io)
{
    return io;
}

Returns self.

See also #to_i #tty? #tell #ungetbyte also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.0