def gen(self):
data_hash = self.get_hash()<EOL>return "<STR_LIT>".format(prefix=self._prefix, hash=data_hash)<EOL>
Generate stable LogicalIds based on the prefix and given data. This method ensures that the logicalId is
deterministic and stable based on input prefix & data object. In other words:

    logicalId changes *if and only if* either the `prefix` or `data_obj` changes

Internally we simply use a SHA1 of the data and append to the prefix to create the logicalId.

NOTE: LogicalIDs are how CloudFormation identifies a resource. If this ID changes, CFN will delete and
      create a new resource. This can be catastrophic for most resources. So it is important to be *always*
      backwards compatible here.


:return: LogicalId that can be used to construct resources
:rtype string