def change_password(username, new_password):
    """
    Change password for given `username`.

    Args:
        username (str): User's name.
        new_password (str): User's new password.
    """
    assert username in passwd_reader.load_users(),\
           "Username '%s' not found!" % username

    sh.ftpasswd(
        "--change-password",
        passwd=True,        # passwd file, not group file
        name=username,
        stdin=True,         # tell ftpasswd to read password from stdin
        file=settings.LOGIN_FILE,
        _in=new_password
    )

    reload_configuration()
Change password for given `username`.

    Args:
        username (str): User's name.
        new_password (str): User's new password.