Just FYI for anyone reviewing this -- in order to be Python 2 and 3 compatible at the same time, I was forced to use the character directly and not use the `\u2212` syntax in the string.  Python 2 would convert that to a unicode character, but Python 3 does not process '\u' in a raw string.  The alternative would be to use a non-raw string here, but then all those slashes have to be doubled and the regex becomes much less readable.  Hence the comment, since it might not be very clear (depending on fonts) that there is a "minus" followed by a "hyphen" in that string.