code: def entity(self, attr, schema=None):
          
          try:
              return self._cache[attr]
          except KeyError, ke:
              return self.map_to(attr, tablename=attr, schema=schema)
docs: Return the named entity from this :class:`.SQLSoup`, or 
          create if not present.
  
          For more generalized mapping, see :meth:`.map_to`.