class_docstr: A data structure to represent a parse tree
class_docstr_tok: ["A","data","structure","to","represent","a","parse","tree"]
docstr: Walks over all of the trees and gets all of the unique tags from the trees
docstr_tok: ["Walks","over","all","of","the","trees","and","gets","all","of","the","unique","tags","from","the","trees"]
code: def get_unique_tags(trees):
      """
      Walks over all of the trees and gets all of the unique tags from the trees
      """
      if isinstance(trees, Tree):
          trees = [trees]
  
      tags = set()
      for tree in trees:
          tree.visit_preorder(preterminal=lambda x: tags.add(x.label))
      return sorted(tags)
  
imports: from collections import deque, Counter
  from enum import Enum
  from io import StringIO
  import itertools
  import re
  import warnings
  from stanza.models.common.stanza_object import StanzaObject
label_desc: Use image node_id 16 for calling the Tree obj's underlying member method code with example usage: obj.get_unique_tags(trees) and returns: sorted