code: def get_n_positions_from_options(opt: Opt):
      """
      Determine n_positions from options dict.
      """
      if opt.get("n_positions"):
          # if the number of positions is explicitly provided, use that
          n_positions = opt["n_positions"]
      else:
          # else, use the worst case from truncate
          n_positions = max(
              opt.get("truncate") or 0,
              opt.get("text_truncate") or 0,
              opt.get("label_truncate") or 0,
          )
          if n_positions == 0:
              # default to 1024
              n_positions = 1024
      if n_positions < 0:
          raise ValueError("n_positions must be positive")
      return n_positions
  
imports: import numpy
  import torch
  import torch.nn
  from parlai.core.opt import Opt
label_desc: Use image node_id 3 for calling a global function with example usage: get_n_positions_from_options(opt) and returns: n_positions