class CsmMix implements CsmElement {

    private List<CsmElement> elements;

    public CsmMix(List<CsmElement> elements) {
        if (elements == null) {
            throw new NullPointerException();
        }
        if (elements.stream().anyMatch(Objects::isNull)) {
            throw new IllegalArgumentException("Null element in the mix");
        }
        this.elements = elements;
    }

    public List<CsmElement> getElements() {
        return elements;
    }

    @Override
    public void prettyPrint(Node node, SourcePrinter printer) {
        elements.forEach(e -> e.prettyPrint(node, printer));
    }

    @Override
    public boolean equals(Object o) {<FILL_FUNCTION_BODY>}

    @Override
    public int hashCode() {
        return elements != null ? elements.hashCode() : 0;
    }

    @Override
    public String toString() {
        return elements.stream().map(e -> e.toString()).collect(Collectors.joining(",", "CsmMix[", "]"));
    }
}

        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;
        CsmMix csmMix = (CsmMix) o;
        return elements != null ? elements.equals(csmMix.elements) : csmMix.elements == null;
    
<no_super_class>