file interface I1 { } file interface I2 { } file class C1 : I1 { } public class C2 { } public class C3 : I2 { } file interface IC { } file class C4 { } file class C5 : C4 { } file struct S1 { } file enum E1 { } file delegate void D1(); file record R1 { } file record struct RS1 { }