def METHOD_NAME(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