code: def _make_ga_mask(ilen, olen, sigma):
      grid_x, grid_y = torch.meshgrid(
          torch.arange(olen).to(olen), torch.arange(ilen).to(ilen)
      )
      grid_x, grid_y = grid_x.float(), grid_y.float()
      return 1.0 - torch.exp(
          -((grid_y / ilen - grid_x / olen) ** 2) / (2 * (sigma**2))
      )
  
imports: import math
  import numpy
  import torch
  from torch import nn
  from inspect import signature
  from torch.nn import functional
  from TTS.tts.utils.generic_utils import sequence_mask
  from TTS.tts.utils.ssim import ssim
label_desc: Use image node_id 4 for calling the GuidedAttentionLoss obj's underlying member method code with example usage: obj._make_ga_mask(ilen, olen, sigma) and returns: unknown