pkg p4, func Clone //deprecated
pkg p4, func Clone[$0 interface{ ~[]$1 }, $1 interface{}]($0) $0
pkg p4, func NewPair[$0 interface{ M }, $1 interface{ ~int }]($0, $1) Pair[$0, $1]
pkg p4, method (Pair[$0, $1]) First() $0
pkg p4, method (Pair[$0, $1]) Second() $1

import java.util.Objects;
import org.jspecify.annotations.Nullable;

/**
 * An immutable pair representing the two endpoints of an edge in a graph. The {@link EndpointPair}
 * of a directed edge is an ordered pair of nodes ({@link #source()} and {@link #target()}). The
 * {@link EndpointPair} of an undirected edge is an unordered pair of nodes ({@link #nodeU()} and
 * {@link #nodeV()}).
 *

      omitEmptyValues = true;
      return this;
    }

    /**
     * Adds a name/value pair to the formatted output in {@code name=value} format. If {@code value}
     * is {@code null}, the string {@code "null"} is used, unless {@link #omitNullValues()} is
     * called, in which case this name/value pair will not be added.
     */
    @CanIgnoreReturnValue

            result.setAttributes(source.entrySet()
                    .stream()
                    .filter(e -> !"name".equals(e.getKey()))
                    .map(e -> new Pair<>(e.getKey(), (String) e.getValue()))
                    .collect(Collectors.toMap(Pair::getFirst, Pair::getSecond)));
            return result;
        } catch (InstantiationException | IllegalAccessException e) {

         * @param field the field name to split
         * @return a Pair containing the field name and extension key
         */
        protected Pair<String, String> splitField(final String defaultField, final String field) {
            final int indexOf = field.indexOf(':');
            if (indexOf < 0) {
                return new Pair<>(field, null);
            }

  }

  /**
   * Asserts that a Unicode escaper escapes the given hi/lo surrogate pair into the expected string.
   *
   * @param escaper the non-null escaper to test
   * @param expected the expected output string
   * @param hi the high surrogate pair character
   * @param lo the low surrogate pair character
   */
  public static void assertUnicodeEscaping(

  }

  /**
   * Asserts that a Unicode escaper escapes the given hi/lo surrogate pair into the expected string.
   *
   * @param escaper the non-null escaper to test
   * @param expected the expected output string
   * @param hi the high surrogate pair character
   * @param lo the low surrogate pair character
   */
  public static void assertUnicodeEscaping(

  }

  @CollectionFeature.Require(SERIALIZABLE)
  public void testInverseSerialization() {
    BiMapPair<K, V> pair = new BiMapPair<>(getMap());
    BiMapPair<K, V> copy = SerializableTester.reserialize(pair);
    assertEquals(pair.forward, copy.forward);
    assertEquals(pair.backward, copy.backward);
    assertSame(copy.backward, copy.forward.inverse());
    assertSame(copy.forward, copy.backward.inverse());
  }

   * always adds a new key-value pair and increases the multimap size by 1. Other implementations
   * prohibit duplicates, and storing a key-value pair that's already in the multimap has no effect.
   *
   * @return {@code true} if the method increased the size of the multimap, or {@code false} if the
   *     multimap already contained the key-value pair and doesn't allow duplicates
   */
  @CanIgnoreReturnValue

  /**
   * Returns the population covariance of the values. The count must be non-zero.
   *
   * <p>This is guaranteed to return zero if the dataset contains a single pair of finite values. It
   * is not guaranteed to return zero when the dataset consists of the same pair of values multiple
   * times, due to numerical errors.
   *
   * <h3>Non-finite values</h3>
   *