code: def _get_event(self, event, find_str):
          
          # Get the term with the given element id
          element = event.find(find_str)
          if element is None:
              return None
          element_id = element.attrib.get('id')
          element_term = self.tree.find("*[@id='%s']" % element_id)
          if element_term is None:
              return None
          time, location = self._extract_time_loc(element_term)
  
          # Now see if there is a modifier like assoc-with connected
          # to the main concept
          assoc_with = self._get_assoc_with(element_term)
  
          # Get the element's text and use it to construct a Concept
          element_text_element = element_term.find('text')
          if element_text_element is None:
              return None
          element_text = element_text_element.text
          element_db_refs = {'TEXT': element_text}
          element_name = sanitize_name(element_text)
  
          element_type_element = element_term.find('type')
          if element_type_element is not None:
              element_db_refs['CWMS'] = element_type_element.text
              # If there's an assoc-with, we tack it on as extra grounding
              if assoc_with is not None:
                  element_db_refs['CWMS'] += ('|%s' % assoc_with)
  
          concept = Concept(element_name, db_refs=element_db_refs)
          if time or location:
              context = WorldContext(time=time, geo_location=location)
          else:
              context = None
          event_obj = Event(concept, context=context)
          return event_obj
docs: Get a concept referred from the event by the given string.