def METHOD_NAME(self) -> str:
    """:class:`str`: Returns the URL of the emoji, if it is custom.
    If this isn't a custom emoji then an empty string is returned
    """
    if self.is_unicode_emoji():
        return ''
    fmt = 'gif' if self.animated else 'png'
    return f'{Asset.BASE}/emojis/{self.id}.{fmt}'