old_contents: /**
   * Copyright 2015 CANAL+ Group
   *
   * Licensed 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.
   */
  
  import { EncryptedMediaError } from "../../errors";
  import log from "../../utils/log";
  import { createEME, onEncrypted } from "../eme";
  
  /**
   * Perform EME management if needed.
   * @returns {Observable}
   */
  function createEMEIfKeySystems(videoElement, keySystems, errorStream) {
    if (keySystems && keySystems.length) {
      return createEME(videoElement, keySystems, errorStream);
    } else {
      return onEncrypted(videoElement).map(() => {
        log.error("eme: ciphered media and no keySystem passed");
        throw new EncryptedMediaError("MEDIA_IS_ENCRYPTED_ERROR", null, true);
      });
    }
  }
  
  export default createEMEIfKeySystems;
  
new_contents: /**
   * Copyright 2015 CANAL+ Group
   *
   * Licensed 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.
   */
  
  import { EncryptedMediaError } from "../../errors";
  import log from "../../utils/log";
  import { createEME, onEncrypted } from "../eme";
  
  /**
   * Perform EME management if needed.
   * @param {HTMLMediaElement} videoElement
   * @param {Array.<Object>} [keySystems]
   * @param {Subject} errorStream
   * @returns {Observable}
   */
  function createEMEIfKeySystems(videoElement, keySystems, errorStream) {
    if (keySystems && keySystems.length) {
      return createEME(videoElement, keySystems, errorStream);
    } else {
      return onEncrypted(videoElement).map(() => {
        log.error("eme: ciphered media and no keySystem passed");
        throw new EncryptedMediaError("MEDIA_IS_ENCRYPTED_ERROR", null, true);
      });
    }
  }
  
  export default createEMEIfKeySystems;
  
subject: add documentation