def maxval(self):
        """
        The maximum value representable by this type.
        """
        if self.signed:
            return (1 << (self.bitwidth - 1)) - 1
        else:
            return (1 << self.bitwidth) - 1

        The maximum value representable by this type.
        
numba/core/types/new_scalars/machine_types.py