If the user does not provide any --version <segno --version> or version <segno.make.version> keyword parameter for segno.make, Segno uses the minimal possible (Micro) QR Code symbol with a maximal error correction level. The QR Code version dominates, meaning that Segno will never choose a better error correction level if this choice requires a higher (Micro) QR Code version.
If the user provides the --error <segno --error> (or error <segno.make.error> keyword for segno.make), the error correction level is treated as minimal error correction level.
To prevent any error correction level enhancement, Segno provides the --no-error-boost <segno --no-error-boost> option and boost_error=False <segno.make.boost_error> option for segno.make.
It's recommended to keep the error level correction boosting, because a better error correction level improves the probability that the QR Code can be read by average QR Code decoders under all circumstances.
Keeping the default (boost error level on):
>>> import segno
>>> qrcode = segno.make('The Long and Winding Road')
>>> qrcode.designator
'2-M'Segno returns a 2-M QR code (version 2, error correction level "M").
If the user does not allow any enhancement of the error correction level, Segno returns a 2-L QR code (version 2, error correction level "L") which does not optimally exploit the possible error corrections:
>>> import segno
>>> qrcode = segno.make('The Long and Winding Road', boost_error=False)
>>> qrcode.designator
'2-L'
As shown, both QR codes use the same version (and are therefore have the same size). However, the first QR code uses a better error correction level (15% vs. 7%) and should be easier to read.