Fix whitespace

README.md

@@ -70,7 +70,6 @@ mapped to playing cards, similar to the Solitaire cipher [2]. Using playing
 cards could be more innocuous and easily explainable to the secret police than 
 a set of peculiar numbered tiles. 
 
-
 ```
 0 a b c d e f
 g h i j k l m

lc4.py

@@ -59,6 +59,7 @@ letters6card = "#abcdefghijklmnopqrstuvwxyz_23456789"
 letters7     = "_abcdefghijklmnopqrstuvwxyz.0123456789,-+*/:?!'()"
 letters7card = "0abcdefghijklmnopqrstuvwxyz_.,-+*/:?!'()123456789"
 
+
 def missing_letters(s,t):
     return ''.join(sorted(set(c for c in s if c not in t)))