class_docstr: Counter with support for nan values.
class_docstr_tok: ["Counter","with","support","for","nan","values","."]
code: def __missing__(self, key):
      if hasattr(self, "nan_count") and is_scalar_nan(key):
          return self.nan_count
      raise KeyError(key)
  
imports: from collections import Counter
  from contextlib import suppress
  from typing import NamedTuple
  import numpy
  from .None import is_scalar_nan
label_desc: Use image node_id 3 for calling the _NaNCounter obj's underlying member method code with example usage: obj.__missing__(key) and returns: self