PSBT is in correct format
++ encode
|= [=rawtx =txid inputs=(list in:psbt) outputs=(list out:psbt)]
^- base64:psbt
+ =/ sep=(unit bytc) `1^0x0
=/ final=(list (unit bytc))
- %+ join `(unit bytc)`[~ 1^0x0]
+ %+ join sep
%+ turn
%- zing
:~ ~[(globals:en rawtx)]
%- base64:en
%- cat:byt
%+ weld ~[[5 0x70.7362.74ff]]
- (murn final same)
+ (murn (snoc final sep) same)
::
++ parse
|= psbt-base64=cord
