def build_filter
      raise(ArgumentError, 'Cannot supply both a filter and an exclusion filter') if include_filter && exclude_filter

      filter                  = where_filter
      (filter ||= {})['_type'] = include_filter if include_filter
      (filter ||= {})['_type'] = {'$not' => exclude_filter} if exclude_filter
      filter
    end
def build_filter
      raise(ArgumentError, 'Cannot supply both a filter and an exclusion filter') if include_filter && exclude_filter

      filter                  = where_filter
      (filter ||= {})['_type'] = include_filter if include_filter
      (filter ||= {})['_type'] = {'$not' => exclude_filter} if exclude_filter
      filter
    end
Returns [Hash] a where clause filter to apply to this server.
 Returns nil if no filter should be applied