public ObjectNode expectNumberMember(String key, Consumer<Number> consumer) {
        consumer.accept(expectNumberMember(key).getValue());
        return this;
    }
Requires that {@code key} exists, is a number, and passes the value to {@code consumer}.

@param key Key to retrieve.
@param consumer Consumer that accepts the number value.
@return Returns the node.
smithy-model/src/main/java/software/amazon/smithy/model/node/ObjectNode.java