input: Write a function to remove all vowels from a given string and return the modified string.  
  assert strip_vowels('') == ''  
  assert strip_vowels("abcdef\nghijklm") == 'bcdf\nghjklm'  
  assert strip_vowels('fedcba') == 'fdcb'  
  assert strip_vowels('eeeee') == ''  
  assert strip_vowels('acBAA') == 'cB'  
  assert strip_vowels('EcBOO') == 'cB'  
  assert strip_vowels('ybcd') == 'ybcd'
output: def strip_vowels(s):
      vowels = "aeiouAEIOU"
      return ''.join([char for char in s if char not in vowels])