hex encoded, 36 chars: 123e4567-e89b-12d3-a456-426655440000
base64 encoded, 22 chars: Ej5FZ-ibEtOkVkJmVUQAAA
GoLang:"base64.RawURLEncoding produces a base64 string (without padding) which is safe for URL inclusion, because the 2 extra chars in the symbol table (beyond [0-9a-zA-Z]) are - and _, both which are safe to be included in URLs"
"encoding/base64" ... uid
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