How to do a fast range scan on a prefix

[jeremy p]

Assume that my keys look like this :
bar:0
bar:1
bar:2
baz:0
baz:1
foo:0
foo:1
foo:2

How do I do a fast range scan that returns all the rows that begin with
"baz:"?  Assume that I know nothing about any of the other rows in the
table.

Thanks for taking a look!

--Jeremy