Right now under the read/write/update section of the readme, there is the following text:

To update a file you need the blob SHA of the previous commit:

but the code that follows does not show how to get that SHA at all, it just shows a meaningless dummy sha. Can that example be updated to show how to actually get the previous commit sha? (Do we use fetch? do we call something on commits? I can't tell =S)

(Also, the section is titled read/write/update but the examples shown only show off reading and updating. Plain writing does not appear as one of the examples)