Set::SubclassCompatible#replace

# File tmp/rubies/ruby-4.0.0/lib/set/subclass_compatible.rb, line 62
def replace(enum)
  if enum.instance_of?(self.class)
    super
  else
    do_with_enum(enum)  # make sure enum is enumerable before calling clear
    clear
    merge(enum)
  end
end