code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium.support.ui;
  
  import java.util.function.Function;
  
  /**
   * A generic interface for waiting until a condition is true or not null. The condition may take a
   * single argument of type .
   *
   * @param <F> the argument to pass to any function called
   */
  public interface Wait<F> {
  
    /**
     * Implementations should wait until the condition evaluates to a value that is neither null nor
     * false. Because of this contract, the return type must not be Void.
     *
     * <p>If the condition does not become true within a certain time (as defined by the implementing
     * class), this method will throw a non-specified {@link Throwable}. This is so that an
     * implementor may throw whatever is idiomatic for a given test infrastructure (e.g. JUnit4 would
     * throw {@link AssertionError}).
     *
     * @param <T> the return type of the method, which must not be Void
     * @param isTrue the parameter to pass to the {@link ExpectedCondition}
     * @return truthy value from the isTrue condition
     */
    <T> T until(Function<? super F, T> isTrue);
  }
  