def _rm_is_valid_annotation_line(line):
for c in line:<EOL><INDENT>if c not in REPEATMASKER_VALID_ANN_CHARS:<EOL><INDENT>return False<EOL><DEDENT><DEDENT>return True<EOL>
:return: True if the line contains only valid annotation characters (defined
         in REPEATMASKER_VALID_ANN_CHARS), otherwise False