fix translate code

in translate use // intead of / due to python3
in translate2 use translate DRY

source/_static/code/translate.py

-genetic_code = {  'ttt': 'F', 'tct': 'S', 'tat': 'Y', 'tgt': 'C',
+genetic_code = { 'ttt': 'F', 'tct': 'S', 'tat': 'Y', 'tgt': 'C',
            'ttc': 'F', 'tcc': 'S', 'tac': 'Y', 'tgc': 'C',
            'tta': 'L', 'tca': 'S', 'taa': '*', 'tga': '*',
            'ttg': 'L', 'tcg': 'S', 'tag': '*', 'tgg': 'W',
@@ -23,7 +23,11 @@ def translate(nuc_seq, code):
     # to avoid to compute len(seq)/3 at each loop
     # I compute it once and use a reference
     # it could be expensive if the sequence is very long.
-    cycle = len(nuc_seq)/3
+
+    # another way to determine the end of looping
+    # stop_iteration = len(nuc_seq)
+    # while (start + 2) < stop_iteration:
+    cycle = len(nuc_seq)//3
     while n < cycle:
         start = n * 3
         end = start + 3
@@ -34,23 +38,18 @@ def translate(nuc_seq, code):
         else:
             raise RuntimeError("unknow codon: " + codon)
         n += 1
+        # if use the other looping solution
+        # n += 3
     return prot_seq
         
 def translate2(nuc_seq, code, phase = 1):
     prot_seq = ''
     if 0 < phase < 4 :
         start = phase - 1
+        nuc_seq = nuc_seq[start:]
     elif -4 < phase < 0:
         start = -phase - 1
         nuc_seq = nuc_seq[::-1]
-    # an other way to determine the end of looping
-    stop_iteration = len(nuc_seq)
-    while (start + 2) < stop_iteration:
-        end = start + 3
-        codon = nuc_seq[start:end].lower()
-        if codon in code:
-            prot_seq += code[codon] 
-        else:
-            raise RuntimeError("unknow codon")
-        start += 3        
+        nuc_seq = nuc_seq[start:]
+    prot_seq = translate(nuc_seq, code)
     return prot_seq