code: def get_filtered_vts_list(self, vts, vt_filter):
          
          if not vt_filter:
              raise RequiredArgument('vt_filter: A valid filter is required.')
  
          filters = self.parse_filters(vt_filter)
          if not filters:
              return None
  
          _vts_aux = vts.copy()
          for _element, _oper, _filter_val in filters:
              for vt_id in _vts_aux.copy():
                  if not _vts_aux[vt_id].get(_element):
                      _vts_aux.pop(vt_id)
                      continue
                  _elem_val = _vts_aux[vt_id].get(_element)
                  _val = self.format_filter_value(_element, _elem_val)
                  if self.filter_operator[_oper](_val, _filter_val):
                      continue
                  else:
                      _vts_aux.pop(vt_id)
  
          return _vts_aux
docs: Gets a collection of vulnerability test from the vts dictionary,
          which match the filter.
  
          Arguments:
              vt_filter (string): Filter to apply to the vts collection.
              vts (dictionary): The complete vts collection.
  
          Returns:
              Dictionary with filtered vulnerability tests.