DecodeOrderPreservingVarUint64 decodes the number from the bytes obtained from method 'EncodeOrderPreservingVarUint64'.

EncodeOrderPreservingVarUint64 returns a byte-representation for a uint64 number such that all zero-bits starting bytes are trimmed in order to reduce the length of the array For preserving the order in a default bytes-comparison, first byte contains the number of remaining bytes.