NilClass#nil?

nil.nil? → true

static VALUE
rb_true(VALUE obj)
{
    return Qtrue;
}

Returns true. For all other objects, method nil? returns false.

See also #inspect #rationalize #| #to_a also in 4.1 · 4.0 · 3.4 · 3.2 · 3.1 · 3.0