You may be interested to learn about slice assignment, if you were concerned about all the indexes you were creating with enumeration and what not.
for b in list1 :
b[:]= ["X"+a for a in b]
Though technically this doesn't do assignment in place (it creates a list for the list comprehension) it will effectively update list1 directly, and doesn't require you to then assign list1 = [list comprehension]
If you want to actually supply individual parameters you would use star to pack the variables into a list.
def update_lists(prepend_text, *lists) :
for list in lists :
update_list(prepend_text, list)
def update_list(prepend_text, list) :
for b in list :
b[:]= [prepend_text+a for a in b]
update_lists("X", list1,list2)
Alternatively you can define the function like this:
def update_lists(prepend_text, lists) :
for list in lists :
update_list(prepend_text, list)
and then call the function as
update_lists("X", [list1,list2])
or perhaps better if you create the list of lists dynamically
lists = []
lists.append(list1)
lists.append(list2)
update_lists("X", lists)
Great, thanks! I did it like this: for c in (list1, list2): for b in c: b[:]= ["X" + a for a in b]
Added some stuff on how to use it in a function for multiple lists.