The background is an implementation of __pow__ for a fixed-point decimal number:

SupportsIntOrFloat = Union[SupportsInt, SupportsFloat]

def __pow__(self, other: SupportsIntOrFloat, mod: Any = None) -> Complex:
    if isinstance(other, SupportsInt):
        exp = int(other)
        if exp == other:
            ... handle integer exponent
    if isinstance(other, SupportsFloat):
        # fractional exponent => fallback to float
        return float(self) ** float(other)
    return NotImplemented

I came across SupportsInt and SupportsFloat, because they are used in typeshed as param types for int and float.