text: REACT_ELEMENT_TYPE/**
   * Copyright (c) Facebook, Inc. and its affiliates.
   *
   * This source code is licensed under the MIT license found in the
   * LICENSE file in the root directory of this source tree.
   *
   * @flow
   */
  
  // ATTENTION
  // When adding new symbols to this file,REACT_ELEMENT_TYPE
  // Please consider also adding to 'react-devtools-shared/src/backend/ReactSymbols'
  
  // The Symbol used to tag the ReactElement-like types. If there is no native Symbol
  // nor polyfill, then a plain number is used for performance.
  export let REACT_ELEMENT_TYPE = 0xeac7;
  export let REACT_PORTAL_TYPE = 0xeaca;
  export let REACT_FRAGMENT_TYPE = 0xeacb;
  export let REACT_STRICT_MODE_TYPE = 0xeacc;
  export let REACT_PROFILER_TYPE = 0xead2;
  export let REACT_PROVIDER_TYPE = 0xeacd;
  export let REACT_CONTEXT_TYPE = 0xeace;
  export let REACT_FORWARD_REF_TYPE = 0xead0;
  export let REACT_SUSPENSE_TYPE = 0xead1;
  export let REACT_SUSPENSE_LIST_TYPE = 0xead8;
  export let REACT_MEMO_TYPE = 0xead3;
  export let REACT_LAZY_TYPE = 0xead4;
  export let REACT_SCOPE_TYPE = 0xead7;
  export let REACT_OPAQUE_ID_TYPE = 0xeae0;
  export let REACT_DEBUG_TRACING_MODE_TYPE = 0xeae1;
  export let REACT_OFFSCREEN_TYPE = 0xeae2;
  export let REACT_LEGACY_HIDDEN_TYPE = 0xeae3;
  export let REACT_CACHE_TYPE = 0xeae4;
  
  if (typeof Symbol === 'function' && Symbol.for) {
    const symbolFor = Symbol.for;
    REACT_ELEMENT_TYPE = symbolFor('react.element');
    REACT_PORTAL_TYPE = symbolFor('react.portal');
    REACT_FRAGMENT_TYPE = symbolFor('react.fragment');
    REACT_STRICT_MODE_TYPE = symbolFor('react.strict_mode');
    REACT_PROFILER_TYPE = symbolFor('react.profiler');
    REACT_PROVIDER_TYPE = symbolFor('react.provider');
    REACT_CONTEXT_TYPE = symbolFor('react.context');
    REACT_FORWARD_REF_TYPE = symbolFor('react.forward_ref');
    REACT_SUSPENSE_TYPE = symbolFor('react.suspense');
    REACT_SUSPENSE_LIST_TYPE = symbolFor('react.suspense_list');
    REACT_MEMO_TYPE = symbolFor('react.memo');
    REACT_LAZY_TYPE = symbolFor('react.lazy');
    REACT_SCOPE_TYPE = symbolFor('react.scope');
    REACT_OPAQUE_ID_TYPE = symbolFor('react.opaque.id');
    REACT_DEBUG_TRACING_MODE_TYPE = symbolFor('react.debug_trace_mode');
    REACT_OFFSCREEN_TYPE = symbolFor('react.offscreen');
    REACT_LEGACY_HIDDEN_TYPE = symbolFor('react.legacy_hidden');
    REACT_CACHE_TYPE = symbolFor('react.cache');
  }
  
  const MAYBE_ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
  const FAUX_ITERATOR_SYMBOL = '@@iterator';
  
  export function getIteratorFn(maybeIterable: ?any): ?() => ?Iterator<*> {
    if (maybeIterable === null || typeof maybeIterable !== 'object') {
      return null;
    }
    const maybeIterator =
      (MAYBE_ITERATOR_SYMBOL && maybeIterable[MAYBE_ITERATOR_SYMBOL]) ||
      maybeIterable[FAUX_ITERATOR_SYMBOL];
    if (typeof maybeIterator === 'function') {
      return maybeIterator;
    }
    return null;
  }
  