take_while

static VALUE
lazy_take_while(VALUE obj)
{
    if (!rb_block_given_p()) {
        rb_raise(rb_eArgError, "tried to call lazy take_while without a block");
    }
    return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
                                         lazy_take_while_func, 0),
                           Qnil, 0);
}