fix rev_comp2

source/_static/code/rev_comp2.py

-import string
+
 
 def rev_comp(seq):
     """
@@ -8,6 +8,6 @@ def rev_comp(seq):
     reverse = seq[::-1]
     direct = 'acgtATCG'
     comp = 'tgcaTGCA'
-    table = string.maketrans(direct, comp)
+    table = str.maketrans(direct, comp)
     rev_comp = reverse.translate(table)
     return rev_comp
\ No newline at end of file