mkdtemp missing brackets

[rijobro]

In a few places (e.g., 3rd cell here), we have:

root_dir = tempfile.mkdtemp if directory is None else directory

which is missing the brackets:

root_dir = tempfile.mkdtemp() if directory is None else directory

Might be worth grepping and replacing all mkdtemp[space] with mkdtemp()[space].