def envRegisterFilter(self, name, attr_regex = '<STR_LIT>', default = True):
attrs = {}<EOL>for prefix in ('<STR_LIT>', '<STR_LIT>'):<EOL><INDENT>key = "<STR_LIT>" % (prefix, name)<EOL>val = self._env.get(key)<EOL>if val:<EOL><INDENT>attrs[prefix] = [attr.strip() for attr in val.split('<STR_LIT:U+002C>')]<EOL><DEDENT>else:<EOL><INDENT>attrs[prefix] = []<EOL><DEDENT><DEDENT>self._filters[name] = MuninAttrFilter(attrs['<STR_LIT>'], attrs['<STR_LIT>'], <EOL>attr_regex, default)<EOL>
Register filter for including, excluding attributes in graphs through 
        the use of include_<name> and exclude_<name> environment variables.
        The value of the variables must be a comma separated list of items. 

        @param name:       Name of filter.
                           (Also determines suffix for environment variable name.)
        @param attr_regex: Regular expression string for checking valid items.
        @param default:    Filter default. Applies when the include list is not 
                           defined and the attribute is not in the exclude list.