':param name_id:
:param session_index:
:param requested_context:
:return:'

def get_authn_statements(self, name_id, session_index=None, requested_context=None):

    result = []
    key = sha1(code(name_id)).hexdigest()
    try:
        statements = self.authn[key]
    except KeyError:
        logger.info(('Unknown    subject    %s' % name_id))
        return []
    for statement in statements:
        if session_index:
            if (statement.session_index != session_index):
                continue
        if requested_context:
            if (not context_match(requested_context, statement[0].authn_context)):
                continue
        result.append(statement)
    return result
