I use an iterator to group UCS-2 surrogate characters together.

class SurrogateGroupIter(object):
    def __init__ (self, uni):
        self.uni = uni
        self.len = len (uni)
        self.i = 0
        
    def __iter__ (self):
        return self
    
    def next (self):
        if self.i == self.len:
            raise StopIteration
        ch = self.uni [self.i]
        self.i += 1
        
        if ord(ch) >= 0xD800 and ord(ch) <= 0xDBFF and self.i < self.len:
            next = self.uni[self.i]
            if ord (next) >= 0xDC00 and ord (next) <= 0xDCFF:
                self.i += 1
                return ch + next
        return ch