old_contents: from setuptools import setup, find_packages
  import os
  from iancupy_data import download_file
  
  # Download data
  get_data = input('Do you want to download all data now(y/n)? ')
  if get_data == 'y':
      print('OK, we will download all data')
      download_file.get_dss_image()
      download_file.get_m4()
  elif get_data == 'n':
      print('OK, any data will not be download.')
  
  
  NAME = 'iancupy_data'
  # VERSION should be PEP440 compatible (https://www.python.org/dev/peps/pep-0440/)
  VERSION = '0.0.dev1'
  
  setup(name=NAME,
        version=VERSION,
        description='Data preparation for IANCU Python exercise',
        install_requires=['astropy', 'astroquery'],
        author='Cheng-Chung Chen, PoShih Chiang, Yi-Hao Su',
        author_email='yhsu@astro.ncu.edu.tw',
        license='MIT',
        packages=find_packages(),
        url='https://github.com/Astrohackers-TW/IANCUPyData.git',
        long_description='',
        zip_safe=False,
  )
  
new_contents: from setuptools import setup, find_packages
  import os
  from iancupy_data import download_file
  
  # Download data
  get_data = input('Do you want to download all data now(y/n)? ')
  
  while get_data not in [ 'y', 'n']:
      print('Please input the "y" or "n".')
      get_data = input('Do you want to download all data now(y/n)? ')
  
  if get_data == 'y':
      print('OK, we will download all data')
      download_file.get_dss_image()
      download_file.get_m4()
  elif get_data == 'n':
      print('OK, any data will not be download.')
  
  NAME = 'iancupy_data'
  # VERSION should be PEP440 compatible (https://www.python.org/dev/peps/pep-0440/)
  VERSION = '0.0.dev1'
  
  setup(name=NAME,
        version=VERSION,
        description='Data preparation for IANCU Python exercise',
        install_requires=['astropy', 'astroquery'],
        author='Cheng-Chung Chen, PoShih Chiang, Yi-Hao Su',
        author_email='yhsu@astro.ncu.edu.tw',
        license='MIT',
        packages=find_packages(),
        url='https://github.com/Astrohackers-TW/IANCUPyData.git',
        long_description='',
        zip_safe=False,
  )
  
subject: Add 'while'.