text: import { createSelector } from 'reselect';
  import getPreviousFile from './get-previous-file';
  
  const getPreviousFrameIndex = state => state.files.previousFrameIndex;
  
  const getPreviousFrame = createSelector(
    [getPreviousFile, getPreviousFrameIndex],
    (previousFile, previousFrameIndex) => {
      return (previousFile && previousFile.frames[previousFrameIndex]) || null;
    }
  );
  
  export default getPreviousFrame;
  