def get_csig(self):
        """
        Generate a node's content signature, the digested signature
        of its content.

        node - the node
        cache - alternate node to use for the signature cache
        returns - the content signature
        """
        try:
            return self.ninfo.csig
        except AttributeError:
            pass

        contents = self.get_contents()
        csig = SCons.Util.MD5signature(contents)
        self.get_ninfo().csig = csig
        return csig
Generate a node's content signature, the digested signature
        of its content.

        node - the node
        cache - alternate node to use for the signature cache
        returns - the content signature