[BUG] Pretty printing can break tuples containing a single item when expanding

[willmcgugan]

When pretty printing a tuple with one item, the pretty printing omits the comma necessary to make it a tuple.

For instance if you pretty print (1,) with expand_all=True, you get this:

(
    1
)

Which is no longer a tuple. If the tuple is not expanded then the result is (1,) which is correct.