code: def _VarUInt64ByteSizeNoTag(uint64):
    
    if uint64 <= 0x7f: return 1
    if uint64 <= 0x3fff: return 2
    if uint64 <= 0x1fffff: return 3
    if uint64 <= 0xfffffff: return 4
    if uint64 <= 0x7ffffffff: return 5
    if uint64 <= 0x3ffffffffff: return 6
    if uint64 <= 0x1ffffffffffff: return 7
    if uint64 <= 0xffffffffffffff: return 8
    if uint64 <= 0x7fffffffffffffff: return 9
    if uint64 > UINT64_MAX:
      raise message.EncodeError('Value out of range: %d' % uint64)
    return 10
docs: Returns the number of bytes required to serialize a single varint
    using boundary value comparisons. (unrolled loop optimization -WPierce)
    uint64 must be unsigned.