code: def envCheckFilter(self, name, attr):
          
          flt = self._filters.get(name)
          if flt:
              return flt.check(attr) 
          else:
              raise AttributeError("Undefined filter: %s" % name)
docs: Check if a specific graph attribute is enabled or disabled through 
          the use of a filter based on include_<name> and exclude_<name> 
          environment variables.
          
          @param name: Name of the Filter.
          @param attr: Name of the Attribute.
          @return:     Return True if the attribute is enabled.