gistfile1.txt

[1] pry(main)> show-method Array#dup

From: object.c in Ruby Core (C Method):
Number of lines: 14
Owner: Kernel
Visibility: public

VALUE
rb_obj_dup(VALUE obj)
{
    VALUE dup;

    if (rb_special_const_p(obj)) {
        rb_raise(rb_eTypeError, "can't dup %s", rb_obj_classname(obj));
    }
    dup = rb_obj_alloc(rb_obj_class(obj));
    init_copy(dup, obj);
    rb_funcall(dup, id_init_dup, 1, obj);

    return dup;
}