}
  }

  /**
   * Creates a transposed view of a given table that flips its row and column keys. In other words,
   * calling {@code get(columnKey, rowKey)} on the generated table always returns the same value as
   * calling {@code get(rowKey, columnKey)} on the original table. Updating the original table
   * changes the contents of the transposed table and vice versa.
   *

    Network<Integer, String> transpose = transpose(directedGraph);
    assertThat(transpose).isEqualTo(expectedTranspose);
    assertThat(transpose(transpose)).isSameInstanceAs(directedGraph);
    AbstractNetworkTest.validateNetwork(transpose);

    assertThat(transpose.edgesConnecting(N1, N2)).isEmpty();
    assertThat(transpose.edgeConnecting(N1, N2)).isEmpty();
    assertThat(transpose.edgeConnectingOrNull(N1, N2)).isNull();

import static com.google.common.collect.Tables.immutableCell;
import static com.google.common.collect.Tables.transformValues;
import static com.google.common.collect.Tables.transpose;
import static com.google.common.collect.Tables.unmodifiableRowSortedTable;
import static com.google.common.collect.Tables.unmodifiableTable;
import static java.util.Collections.sort;