Minor docstring tweak to ImageData, to satisfy Sphinx.
Minor docstring tweak to ImageData, to satisfy Sphinx.

I mainly did this to quieten Sphinx error messages, but it's a good example of
the arguments documentation style I've adopted elsewhere.

I suggest it as a standard for the TKP docs that balances clarity and
compactness - comments welcome.

bartscheers/tkp,mkuiack/tkp,mkuiack/tkp,transientskp/tkp,transientskp/tkp,bartscheers/tkp