diff --git a/source/_static/code/restriction.py b/source/_static/code/restriction.py
index 7227b69fa371170323b99ac0c207489eac973f75..91bc798fffcc70ad12ba0e98d7a94936e6a3a6e8 100644
--- a/source/_static/code/restriction.py
+++ b/source/_static/code/restriction.py
@@ -1,8 +1,9 @@
 from operator import itemgetter
 
 # we decide to implement enzyme as tuple with the following structure
-# ("name", "comment", "sequence", "cut", "end")
-#    0         1           2        3      4
+# (name, comment, sequence, cut, end)
+#    0     1         2       3    4
+
 
 def one_enz_one_binding_site(dna, enzyme):
     """
@@ -19,7 +20,7 @@ def one_enz_all_binding_sites(dna, enzyme):
     :param dna: the dna sequence to search enzyme binding sites
     :type dna: str
     :param enzyme: the enzyme to looking for
-    :type enzyme:  a namedtuple RestrictEnzyme
+    :type enzyme:  a tuple (str name, str comment, str sequence, int cut, str end)
     :return: all positions of enzyme binding sites in dna
     :rtype: list of int
     """
@@ -36,7 +37,7 @@ def one_enz_all_binding_sites2(dna, enzyme):
     :param dna: the dna sequence to search enzyme binding sites
     :type dna: str
     :param enzyme: the enzyme to looking for
-    :type enzyme:  a namedtuple RestrictEnzyme
+    :type enzyme:  a tuple (str name, str comment, str sequence, int cut, str end)
     :return: all positions of enzyme binding sites in dna
     :rtype: list of int
     """
@@ -60,8 +61,8 @@ def binding_sites(dna, enzymes):
 
     :param dna: the dna sequence to search enzyme binding sites
     :type dna: str
-    :param enzyme: the enzyme to looking for
-    :type enzyme:  a namedtuple RestrictEnzyme
+    :param enzymes: the enzymes to looking for
+    :type enzymes: a sequence of enzyme tuple
     :return: all positions of each enzyme binding sites in dna
     :rtype: list of int
     """