class Rugged::Blob

def similarity(other)
  other_sig = case other
  when HashSignature
    other
  when String
    HashSignature.new(other)
  when Blob
    other.hashsig
  else
    raise TypeError, "Expected a Rugged::Blob, String or Rugged::Blob::HashSignature"
  end
  HashSignature.compare(self.hashsig, other_sig)
end