*/
@GwtCompatible
final class MathPreconditions {
  @CanIgnoreReturnValue
  static int checkPositive(String role, int x) {
    if (x <= 0) {
      throw new IllegalArgumentException(role + " (" + x + ") must be > 0");
    }
    return x;
  }

  @CanIgnoreReturnValue
  static long checkPositive(String role, long x) {
    if (x <= 0) {
      throw new IllegalArgumentException(role + " (" + x + ") must be > 0");

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.graph.Graphs.checkNonNegative;
import static com.google.common.graph.Graphs.checkPositive;
import static java.util.Objects.requireNonNull;

import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.collect.Sets;

  static long checkNonnegative(long value, String name) {
    if (value < 0) {
      throw new IllegalArgumentException(name + " cannot be negative but was: " + value);
    }
    return value;
  }

  static void checkPositive(int value, String name) {
    if (value <= 0) {
      throw new IllegalArgumentException(name + " must be positive but was: " + value);
    }
  }

  /**

  static long checkNonnegative(long value, String name) {
    if (value < 0) {
      throw new IllegalArgumentException(name + " cannot be negative but was: " + value);
    }
    return value;
  }

  static void checkPositive(int value, String name) {
    if (value <= 0) {
      throw new IllegalArgumentException(name + " must be positive but was: " + value);
    }
  }

  /**