Returns a 2-tuple (behaviour, type).
         behaviours:
          0 - join
          1 - split
          2 - ignore

def _get_token_type(self, char):
        """ Returns a 2-tuple (behaviour, type).
         behaviours:
          0 - join
          1 - split
          2 - ignore
        """
        if char in '()':
            return self.SPLIT, 0
        elif char == ',':
            return self.SPLIT, 1
        elif char in '<>':
            return self.IGNORE, 2
        elif char == '.':
            return self.JOIN, 3
        elif char.isdigit():
            return self.JOIN, 4
        elif char.isalpha():
            return self.JOIN, 5
        elif char == '^':
            return self.JOIN, 6
        elif char.isspace():
            return self.IGNORE, 7
        else:
            raise ValueError('TokeniserException: "{}" can not be tokenised'.format(char))