class_docstr: A constraint that prevents modifications to words less than a certain
  word character-length.
  
  :param min_length: Minimum word character-length needed for changes
      to be made to a word.
class_docstr_tok: ["A","constraint","that","prevents","modifications","to","words","less","than","a","certain","word","character-length",".",":","param","min_length",":","Minimum","word","character-length","needed","for","changes","to","be","made","to","a","word","."]
code: def _get_modifiable_indices(self, current_text):
      idxs = []
      for i, word in enumerate(current_text.words):
          if len(word) >= self.min_length:
              idxs.append(i)
      return set(idxs)
  
imports: from textattack.constraints import PreTransformationConstraint
label_desc: Use image node_id 2 for calling the MinWordLength obj's underlying member method code with example usage: obj._get_modifiable_indices(current_text) and returns: set