class_docstr: Synthetic dataset class. Mean image is returned always. This dataset
  is used/recommended to use for testing purposes only.
  
  Args:
      path (string): can be "" [not used]
      split (string): specify split for the dataset.
          Usually train/val/test. Used to read images if
          reading from a folder `path' and retrieve settings for that split
          from the config path [not used]
      dataset_name (string): name of dataset. For information only. [not used]
      data_source (string, Optional): data source ("synthetic") [not used]
code: def generate_image(seed: int, crop_size: int):
      rng = np.random.RandomState(seed)
      noise_size = crop_size // 16
      gaussian_kernel_radius = rng.randint(
          noise_size // 2, noise_size * 2
      )
      img = Image.fromarray(
          (255 * rng.rand(noise_size, noise_size, 3)).astype(np.uint8)
      )
      img = img.resize((crop_size, crop_size))
      img = img.filter(
          ImageFilter.GaussianBlur(radius=gaussian_kernel_radius)
      )
      return img
  
file_path: vissl/vissl/data/synthetic_dataset.py
imports: from typing import List
  import numpy
  from PIL import Image, ImageFilter
  from torch.utils.data import Dataset
  from vissl.data.data_helper import get_mean_image
label_desc: Use image node_id 7 for calling the SyntheticImageDataset obj's underlying member method code with example usage: obj.generate_image(seed, crop_size) and returns: img