class_docstr: A mask backed by a dense numpy array.
class_docstr_tok: ["A","mask","backed","by","a","dense","numpy","array","."]
code: def __post_init__(self):
      if self.array.ndim != 2:
          raise ValueError("Expected a 2-dim array")
  
      if self.array.dtype != np.bool_:
          raise ValueError("Mask must be a boolean array")
  
imports: from __future__ import annotations
  import dataclasses
  from typing import Any, Callable, Sequence, Tuple
  import numpy
label_desc: Use image node_id 1 for calling the NumpyMask obj's underlying member method code with example usage: obj.__post_init__() without return types