argos-translate score not understood

Question

argos-translate takes for translation: a text and a language ID as an input and returns the translated text and a score as output.

However the score gives values seemingly from $-\infty$ to some smaller numbers.

Question

How is the score value defined / how does it translate to range [0,1]?

What I tried

I tried argos-translate and observed the described range of confidence values (including negative ones).

On SW code level this is the score value in argos-translate/argostranslate/translate.py at master · argosopentech/argos-translate · GitHub

class Hypothesis: """Represents a translation hypothesis

Attributes:
    value: The hypothetical translation value
    score: The score representing the quality of the translation
"""

value: str
score: float

I checked PyPi for an explanation of the score value https://pypi.org/project/argostranslate/1.4.0/ - it is not described?

I googled for an explanation of the score value - I couldn't find anything.