- whitespaces are safe to remove from strings, and is convenient if we do this for users
- bytes-like inputs should be left alone: individual bytes that look like whitespaces can appear in them anywhere
- even stripping the leading/trailing whitespaces is not safe to do: the first byte of the nVersion or the last byte of the nLocktime might look like whitespace too!
- instead, leading/trailing whitespaces can be stripped closer to where they are input, e.g. in the GUI
- e.g. ".txn" files that we ourselves create contain a complete tx as a hex string, with a trailing final newline in the file
- instead of reading that as bytes, we can read it as text
- ".psbt" files OTOH are binary
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