Challenge: Write a function bubble (lst, a = False) that takes one required argument, a list of numbers, sorts the list using the bubble method, and returns the resulting list.

The desc argument specifies the sort order. If it is True, then the function sorts in descending order, if it is False, then it sorts in ascending order.

By default, the function sorts the list in ascending order.

It is forbidden to use the built-in features of the language for sorting.

All you need is the I / O function, no need to implement

Tell me, pzhl, what’s wrong with my version?

```
def bubble (lst, a = False):
if a:
for i in range (len (lst) -1):
for j in range (len (lst) -i-1):
if lst [j] & gt; lst [j + 1]:
lst [j], lst [j + 1] = lst [j + 1], lst [j]
elif not a:
for i in range (len (lst) -1):
for j in range (len (lst) -i-1):
if lst [j] & lt; lst [j + 1]:
lst [j], lst [j + 1] = lst [j + 1], lst [j]
return lst
```

## Answer 1

```
def bubble (lst, desc = False):
if (not desc):
for i in range (len (lst) -1):
for j in range (len (lst) -i-1):
if lst [j] & gt; lst [j + 1]:
lst [j], lst [j + 1] = lst [j + 1], lst [j];
else:
for i in range (len (lst) -1):
for j in range (len (lst) -i-1):
if lst [j] & lt; lst [j + 1]:
lst [j], lst [j + 1] = lst [j + 1], lst [j];
return lst;
```