class Protocol::HTTP::Body::Digestable

def initialize(body, digest = Digest::SHA256.new, callback = nil)

@parameter callback [Block] The callback is invoked when the digest is complete.
@parameter digest [Digest] the digest to use.
@parameter body [Readable] the body to wrap.

Initialize the digestable body with a callback. 
def initialize(body, digest = Digest::SHA256.new, callback = nil)
	super(body)
	
	@digest = digest
	@callback = callback
end