"""A list of declarations, surrounded by braces.
   Unlike class bodies, interface bodies can’t immediately contain runnable code,
   so the [[content]] is just declarations, no statements.
   An exception from this are specifications, which, while technically statements,
   are allowed (shortcut refinement).
   An interface body may also include a list of [[imports]]
   that is local to this interface body only.
   Examples (multi-line):
           shared formal Other plus(Other other);
           shared default void writeString(String string) => print(string);
           shared default void write(Anything that) => writeString(that?.string else "<null>");
           shared formal String name;
           string => name;
shared class InterfaceBody(content, imports = [])
        extends Body() {
    shared actual Import[] imports;
    shared actual <Declaration|Specification>[] content;
    shared actual <Import|Declaration|Specification>[] children = concatenate(imports, content);
    shared actual Result transform<out Result>(Transformer<Result> transformer)
            => transformer.transformInterfaceBody(this);
    shared actual void visit(Visitor visitor)
            => visitor.visitInterfaceBody(this);
    shared actual Boolean equals(Object that) {
        if (is InterfaceBody that) {
            return imports==that.imports && content==that.content;
        } else {
            return false;
    shared actual Integer hash
            => 31 * (imports.hash + 31*content.hash);
    shared InterfaceBody copy(<Declaration|Specification>[] content = this.content, Import[] imports = this.imports) {
        value ret = InterfaceBody(content, imports);
        return ret;