/guava/guava/src/com/google/common/collect/TreeBasedTable.java
checkArgument ( rangeContains ( checkNotNull ( fromKey ) ) ) ; return new TreeRow ( rowKey, fromKey, upperBound ) ;
public SortedMap<C, V> headMap(C toKey) { checkArgument(rangeContains(checkNotNull(toKey))); return new TreeRow(rowKey, lowerBound, toKey); } @Override public SortedMap<C, V> tailMap(C fromKey) { <extra_id_0> } @Override public C firstKey() { updateBackingRowMapField(); if (backingRowMap == null) { throw new NoSuchElementException();