code: def __len__(self) -> int:
      if len(self.pmf) != self.domain.size:
          raise ValueError("pmf and domain must have the same length")
      return len(self.pmf)
  
imports: from dataclasses import dataclass
  from typing import Tuple
  import numpy
  from scipy import integrate
  from scipy.special import erfc
  from ..rdp import _compute_rdp
  from .domain import Domain
label_desc: Use image node_id 1 for calling the DiscretePRV obj's underlying member method code with example usage: obj.__len__() and returns: len