code: def from_list(cls, dict_list, log=None):
      if not isinstance(dict_list, (tuple, list)) or not all(
          isinstance(x, dict) for x in dict_list
      ):
          raise ValueError(
              "Expecting a list of configurations dictionaries"
          )
      configs = [cls(**entry) for entry in dict_list]
      valid_configs = [conf for conf in configs if conf.is_valid()]
      if log and len(valid_configs) < len(configs):
          log.warning(
              "Invalid bucket configurations detected for {}".format(
                  ", ".join(
                      "/".join((config.host, config.bucket))
                      for config in configs
                      if config not in valid_configs
                  )
              )
          )
      return valid_configs
  
imports: import abc
  import warnings
  from copy import copy
  from operator import itemgetter
  from os import getenv
  import furl
  import six
  from attr import attrib, attrs
label_desc: Use image node_id 4 for calling the S3BucketConfig obj's underlying member method code with example usage: obj.from_list(cls, dict_list, log) and returns: valid_configs