old_contents: import lzma
  
  x = open('examples/txt/1.txt', 'rb').read() # file 1 of any type
  y = open('examples/txt/3.txt', 'rb').read() # file 2 of the same type as file 1
  x_y = x + y # the concatenation of files
  
  x_comp = lzma.compress(x) # compress file 1
  y_comp = lzma.compress(y) # compress file 2
  x_y_comp = lzma.compress(x_y) # compress file concatenated
  
  # print len() of each file
  print(len(x_comp), len(y_comp), len(x_y_comp), sep=' ', end='\n')
  
  # magic happens here
  ncd = (len(x_y_comp) - min(len(x_comp), len(y_comp))) / max(len(x_comp), len(y_comp))
  
  print(ncd)
  
new_contents: import lzma
  import sys
  
  x = open(sys.argv[1], 'rb').read()  # file 1 of any type
  y = open(sys.argv[2], 'rb').read()  # file 2 of the same type as file 1
  x_y = x + y  # the concatenation of files
  
  x_comp = lzma.compress(x)  # compress file 1
  y_comp = lzma.compress(y)  # compress file 2
  x_y_comp = lzma.compress(x_y)  # compress file concatenated
  
  # print len() of each file
  print(len(x_comp), len(y_comp), len(x_y_comp), sep=' ', end='\n')
  
  # magic happens here
  ncd = (len(x_y_comp) - min(len(x_comp), len(y_comp))) / \
      max(len(x_comp), len(y_comp))
  
  print(ncd)
  
subject: Add file as parameters