hook arguments/documentation error?

[handler]

i'm having trouble figuring out the usage of hooks. in the
documentation it shows this:

1 class Post
2 include DataMapper::Resource
3
4 # ... key and properties here
5
6 # This record will save properly
7 before :save do |post|
8 true
9 end
10

(from http://datamapper.org/docs/callbacks)

but when i do this, the object passed into the block is the value
"true", ie:

before :save do |post|
puts post
end

puts "true" to the console

am i doing it wrong?