class_docstr: A list-like object with feature names. It allows
  feature names for unknown features to be generated using
  a provided template, and to avoid making copies of large objects
  in get_feature_names.
class_docstr_tok: ["A","list-like","object","with","feature","names",".","It","allows","feature","names","for","unknown","features","to","be","generated","using","a","provided","template",",","and","to","avoid","making","copies","of","large","objects","in","get_feature_names","."]
code: def __getitem__(self, idx):
      if isinstance(idx, slice):
          return self._slice(idx)
      if isinstance(idx, np.ndarray):
          return [self[i] for i in idx]
      if self.has_bias and idx == self.bias_idx:
          return self.bias_name
      if 0 <= idx < self.n_features:
          try:
              return self.feature_names[idx]
          except (TypeError, KeyError, IndexError):
              return self.unkn_template % idx
      raise IndexError("Feature index out of range")
  
file_path: eli5/eli5/_feature_names.py
imports: import re
  import six
  from typing import Any, Iterable, Iterator, Tuple, Sized, List, Optional, Dict, Union, Callable, Pattern
  import numpy
  import scipy.sparse
label_desc: Use image node_id 5 for calling the FeatureNames obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self, unknown, self, self, unknown