from typing import Callable
from torch import nn
import torch


class ScaledSigmoid(nn.Sigmoid):
    """ Scaled sigmoid function.
    """

    def __init__(self, scale: float = 1.0):
        super().__init__()
        self._scale = scale

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        return super().forward(self._scale * x)

    @staticmethod
    def get_factory(scale: float = 1.0) -> Callable[[], 'ScaledSigmoid']:
        """ Returns a function that creates a scaled sigmoid module.
        """
        return lambda: ScaledSigmoid(scale)