def _validate_name(name):
    """Pre-flight ``Bucket`` name validation.

    :type name: str or :data:`NoneType`
    :param name: Proposed bucket name.

    :rtype: str or :data:`NoneType`
    :returns: ``name`` if valid.
    """
    if name is None:
        return

    # The first and las characters must be alphanumeric.
    if not all([name[0].isalnum(), name[-1].isalnum()]):
        raise ValueError("Bucket names must start and end with a number or letter.")
    return name
Pre-flight ``Bucket`` name validation.

    :type name: str or :data:`NoneType`
    :param name: Proposed bucket name.

    :rtype: str or :data:`NoneType`
    :returns: ``name`` if valid.