An interface definition or alias.

Examples (multi-line):

shared interface Printable {
    shared default void print() => package.print(this);
}

shared interface People => {Person*};
Initializer
AnyInterface()
Inherited Attributes
Attributes inherited from: ClassOrInterface
Attributes inherited from: Declaration
Attributes inherited from: Node
Attributes inherited from: Object
hash, string
Attributes inherited from: TypeDeclaration
Inherited Methods
Methods inherited from: Node
Methods inherited from: Object
equals