code: def list_cache_subnet_groups(region=None, key=None, keyid=None, profile=None):
      '''
      Return a list of all cache subnet group names
  
      Example:
  
      .. code-block:: bash
  
          salt myminion boto3_elasticache.list_cache_subnet_groups region=us-east-1
      '''
      return [g['CacheSubnetGroupName'] for g in
              describe_cache_subnet_groups(None, region, key, keyid, profile)f list_cache_subnet_groups(region=None, key=None, keyid=None, profile=None):
      '''
      Return a list of all cache subnet group names
  
      Example:
  
      .. code-block:: bash
  
          salt myminion boto3_elasticache.list_cache_subnet_groups region=us-east-1
      '''
      return [g['CacheSubnetGroupName'] for g in
              describe_cache_subnet_groups(None, region, key, keyid, profile)]
docs: Return a list of all cache subnet group names
  
      Example:
  
      .. code-block:: bash
  
          salt myminion boto3_elasticache.list_cache_subnet_groups region=us-east-1