So my final definition for ShiftLayer is
class ShiftLayer(nn.Module):
    def __init__(self, b):
        super().__init__()
        self.b = nn.Parameter(torch.tensor(...))
        
    def forward(self, x):
        return x + self.b

However, this gives me an error:
 self.b = nn.Parameter(torch.tensor(...)),                                                                                                ^                                                                                                                               
SyntaxError: expression cannot contain assignment, perhaps you meant "=="?  

Not sure how else I would assign b as a parameter