code: async def _match_idens(self, core, prefix):
          '''
          Returns the iden that starts with prefix.  Prints out error and returns None if it doesn't match
          exactly one.
          '''
          idens = [iden for iden, trig in await core.listTriggers()]
          matches = [iden for iden in idens if iden.startswith(prefix)]
          if len(matches) == 1:
              return matches[0]
          elif len(matches) == 0:
              self.printf('Error: provided iden does not match any valid authorized triggers')
          else:
              self.printf('Error: provided iden matches more than one trigger')
          return Nonync def _match_idens(self, core, prefix):
          '''
          Returns the iden that starts with prefix.  Prints out error and returns None if it doesn't match
          exactly one.
          '''
          idens = [iden for iden, trig in await core.listTriggers()]
          matches = [iden for iden in idens if iden.startswith(prefix)]
          if len(matches) == 1:
              return matches[0]
          elif len(matches) == 0:
              self.printf('Error: provided iden does not match any valid authorized triggers')
          else:
              self.printf('Error: provided iden matches more than one trigger')
          return None
docs: Returns the iden that starts with prefix.  Prints out error and returns None if it doesn't match
          exactly one.