text: import React from 'react';
  import PropTypes from 'prop-types';
  import styled, { keyframes } from 'styled-components';
  import Ufobaseplate from './Ufobaseplate';
  import Ufotop from './Ufotop';
  import { gameHeight } from '../utils/constants';
  
  const moveVertically = keyframes`
    0% {
      transform: translateY(0);
    }
    100% {
      transform: translateY(${gameHeight}px);
    }
  `;
  
  const Move = styled.g`
    animation: ${moveVertically} 4s linear;
  `;
  
  const Ufo = props => (
    <Move>
      <Ufobaseplate position={props.position} />
      <Ufotop position={props.position} />
    </Move>
  );
  
  Ufo.propTypes = {
    position: PropTypes.shape({
      x: PropTypes.number.isRequired,
      y: PropTypes.number.isRequired
    }).isRequired,
  };
  
  export default Ufo;
  