This will take a given index and work backwards until it encounters a '$' indicating which dollar ID is
        associated with this read
        @param strIndex - the index of the character to start with
        @return - an integer indicating the dollar ID of the string the given character belongs to

def getSequenceDollarID(self, strIndex, returnOffset=False):
        '''
        This will take a given index and work backwards until it encounters a '$' indicating which dollar ID is
        associated with this read
        @param strIndex - the index of the character to start with
        @return - an integer indicating the dollar ID of the string the given character belongs to
        '''
        #figure out the first hop backwards
        currIndex = strIndex
        prevChar = self.getCharAtIndex(currIndex)
        currIndex = self.getOccurrenceOfCharAtIndex(prevChar, currIndex)
        i = 0
        
        #while we haven't looped back to the start
        while prevChar != 0:
            #figure out where to go from here
            prevChar = self.getCharAtIndex(currIndex)
            currIndex = self.getOccurrenceOfCharAtIndex(prevChar, currIndex)
            i += 1
        
        if returnOffset:
            return (currIndex, i)
        else:
            return currIndex