code: def _collect_data_references(self, irsb, irsb_addr):
          
  
          if irsb.data_refs:
              self._process_irsb_data_refs(irsb)
          elif irsb.statements:
              irsb = self._unoptimize_irsb(irsb)
              # for each statement, collect all constants that are referenced or used.
              self._collect_data_references_by_scanning_stmts(irsb, irsb_addr)
docs: Unoptimises IRSB and _add_data_reference's for individual statements or
          for parts of statements (e.g. Store)
  
          :param pyvex.IRSB irsb: Block to scan for data references
          :param int irsb_addr: Address of block
          :return: None