def truncate(self, size):
    """
      truncate this fastqSequence in-place so it is only <size> nucleotides
      long

      :param size: the number of nucleotides to truncate to.
    """
    if size > len(self):
      raise NGSReadError("Trying to truncate NGS read to size " + str(size) +
                         ", but read is only " + str(len(self)) +
                         " nucleotides long")
    if size < 0:
      raise NGSReadError("Trying to truncate NGS read to size less than 0")

    self.trimRight(len(self) - size)