public default <K, V> Iterator<KeyValue<K, V>> head(final String location, final String memoryKey, final Class readerClass) {
        return this.head(location, memoryKey, readerClass, Integer.MAX_VALUE);
    }
Get the {@link KeyValue} data at the specified memory location.

@param location    the root location of the data
@param memoryKey   the memory key
@param readerClass the class of the parser that understands the memory format
@return an iterator of key-values.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/io/Storage.java