def can_user_perform(user, account_id, action):
    """
    Utility method for checking arbitrary actions are applicable to a specific account for a user.
    :param user: A dict object representing user
    :param account: A string representing an AWS account to validate permission for.
    :param action: A string representing an action to check for.
    :return (bool, str): Bool for whether or not permission exists, String for justification.
    """
    if 'accounts' in user and account_id in user['accounts']:
        if 'permissions' in user['accounts'][account_id] and action in user['accounts'][account_id]['permissions']:
            if user['accounts'][account_id]['permissions'][action]:
                return True, 'User has explicit permission for account {}.'.format(account_id)

    return False, 'User does not have rights for account {}.'.format(account_id)