def register_style_sheet(name, sheet):
    """ Register a dock area style sheet.

    Parameters
    ----------
    name : basestring
        The name to associate with the stylesheet for later lookup.

    sheet : unicode
        A unicode string containing the style sheet for the dock area.

    Raises
    ------
    ValueError
        If the given name is already registered, a value error will be
        raised.

    """
    assert isinstance(sheet, unicode), 'style sheet must a unicode string'
    if name in _style_sheets:
        raise ValueError("'%s' style is already registered" % name)
    _style_sheets[name] = sheet


#: A null stylesheet.
dataset/ETHPy150Open ContinuumIO/ashiba/enaml/enaml/qt/docking/style_sheets.py/register_style_sheet/original