Typo: 'local namespace' should be 'global namespace' on page 117

[p-j-smith]

Thanks for the excellent book! I'm enjoying working my way through it.

In Example 6.5 on page 117, I think the following sentence:

This statement takes such a long time per hit because grid_shape must be retrieved from the local namespace

should read:

This statement takes such a long time per hit because grid_shape must be retrieved from the global namespace