implementation none for std::Entity:

end

entity Host:
    string name
    string blurp
end

entity File:
    string name
end

implement Host using none
implement File using none

Host host [1] -- [0:] File files

index Host(name)
index File(host, name)

h1 = Host(name="h1", blurp="blurp1")
h1a1 = Host(name="h1", blurp="blurp2")