def METHOD_NAME(self, offset=0, length=-1):
    """
    :param: offset is zero-based and non-negative
    :param: length must be >= 0
    :returns: phred quality values using ASCII offset of 33
    """
    ngs_str_err = NGS_RawString()
    try:
        ngs_str_seq = NGS_String()
        try:
            res = NGS.lib_manager.PY_NGS_ReadGetReadQualities(self.ref, offset, length, byref(ngs_str_seq.ref), byref(ngs_str_err.ref))
            return ngs_str_seq.getPyString()
        finally:
            ngs_str_seq.close()
    finally:
        ngs_str_err.close()