docstr: :param str folder: path to directory
  :type folder: string
  :param str format: either TEXT or COLUMN
  :type format: str
code: def load(self, folder, format):
      """
  
      :param str folder: path to directory
      :type folder: string
      :param str format: either TEXT or COLUMN
      :type format: str
      """
      ids = listdir(folder)
      files = [join(folder, file) for file in ids]
      contents = []
      for f in files:
          with io.open(f, "r", encoding="utf-8") as f:
              content = f.read().strip()
              contents.append(content)
      documents = []
  
      for id, content in zip(ids, contents):
          document = Document(id)
          unicode_transformer = UnicodeTransformer()
          content = unicode_transformer.transform(content)
          sentences = content.split("\n\n")
          sentences = [self._column_to_text(s) for s in sentences]
          document.set_sentences(sentences)
          documents.append(document)
  
      self.documents = documents
  
file_path: underthesea/underthesea/corpus/ws_corpus.py
imports: import io
  from underthesea.corpus import Document, UnicodeTransformer, Corpus
  from os import listdir, mkdir
  from os.path import join
  from underthesea.util.file_io import write
label_desc: Use image node_id 4 for calling the WSCorpus obj's underlying member method code with example usage: obj.load(folder, format) without return types