return Tables.transformValues(original, TableCollectionTest.FIRST_CHARACTER);
  }

  @Override
  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    Table<String, Integer, String> table = HashBasedTable.create();
    table.put("foo", 1, "apple");
    table.put("bar", 1, "banana");
    table.put("foo", 3, "cat");

    return Tables.transformValues(table, TableCollectionTest.DIVIDE_BY_2);
  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    Table<Character, String, Integer> table = HashBasedTable.create();
    table.put('a', "one", 2);
    table.put('a', "two", 4);
    table.put('a', "three", 6);
    table.put('b', "four", 8);

    return Tables.immutableCell(
        checkNotNull(rowKey, "rowKey"),
        checkNotNull(columnKey, "columnKey"),
        checkNotNull(value, "value"));
  }

  /**
   * A builder for creating immutable table instances, especially {@code public static final} tables
   * ("constant tables"). Example:
   *
   * <pre>{@code

    CollectorTester.of(collector)
        .expectCollects(ImmutableTable.of())
        .expectCollects(
            ImmutableTable.of("one", "uno", 3),
            Tables.immutableCell("one", "uno", 1),
            Tables.immutableCell("one", "uno", 2));
  }

  public void testBuilder() {
    ImmutableTable.Builder<Character, Integer, String> builder = new ImmutableTable.Builder<>();

import com.google.common.base.Supplier;
import java.util.Map;
import java.util.TreeMap;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Test cases for {@link Tables#newCustomTable}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class NewCustomTableTest extends AbstractTableTest<Character> {

  @Override

import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Function;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Test cases for {@link Tables#transformValues}.
 *
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class TablesTransformValuesTest extends AbstractTableTest<Character> {

    super(false, true, true, true, false);
  }

  @Override
  Table<Character, String, Integer> makeTable() {
    Table<String, Character, Integer> original = TreeBasedTable.create();
    return Tables.transpose(original);
  }

import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Function;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Test cases for {@link Tables#transformValues}.
 *
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class TablesTransformValuesTest extends AbstractTableTest<Character> {

## Create the tables

In this case, we are creating the tables in the same Python file, but in production, you would probably want to create them with Alembic, integrated with migrations, etc.

Here, this section would run directly, right before starting your **FastAPI** application.

* Create an `engine`.
* Create all the tables from the `metadata` object.

```Python hl_lines="25-28"

    assertEquals(
        ImmutableTable.of('a', 1, "foo"), builder.put(Tables.immutableCell('a', 1, "foo")).build());
  }

  public void testBuilder_withImmutableCellAndNullContents() {
    ImmutableTable.Builder<Character, Integer, String> builder = new ImmutableTable.Builder<>();
    try {
      builder.put(Tables.immutableCell((Character) null, 1, "foo"));
      fail();
    } catch (NullPointerException e) {