typos

source/Collection_Data_Types.rst

@@ -547,7 +547,7 @@ We also have to define which name correspond to which item::
     import collections
     RestrictEnzyme = collections.namedtuple("RestrictEnzyme", ("name", "comment", "sequence", "cut", "end"))
 
-The we can use this new kind of tuple::
+Then we can use this new kind of tuple::
 
     ecor1 = RestrictEnzyme("EcoRI", "Ecoli restriction enzime I", "gaattc", 1, "sticky")
     ecor5 = RestrictEnzyme("EcoRV", "Ecoli restriction enzime V", "gatatc", 3, "blunt")