higher_order_factory_functions.py

def numin_er(srch_string):
    def inner(mem):
        return srch_string.count(mem)
    return inner

sublist = ('x', 'str', 'a', 'pr')
string = "rprpraxp"

result = sum(map(numin_er(string), sublist))

# although, in this case, you can just pass the
# bound method!

result = sum(map(string.count, sublist))

# overall point: functions are just like any other object
# methods are function objects that carry around the state
# from the object they are bound to.