Right now the documentation for usb_cdc.serial.read() gives the signature as usb_cdc.serial.read(size = 1). That is, it reads a at most a single byte. This does not match the implementation: it actually tries to read as much as possible, because it uses the standard stream operation read(), which has those semantics.

Pyserial's read() has the same signature and does read only one byte if no argument is given. I think our original intention was to match pyserial.

So rather than change the documentation, we should probably fix the implementation.