text: import re
  from nltk.corpus import stopwords
  
  REPLACE_BY_SPACE_RE = re.compile('[/(){}\[\]\|@,;]')
  GOOD_SYMBOLS_RE = re.compile('[^0-9a-z #+_]')
  STOPWORDS = set(stopwords.words('english'))
  def text_prepare(text):
      text = text.lower()
      text = REPLACE_BY_SPACE_RE.sub(' ', text)
      text = GOOD_SYMBOLS_RE.sub('', text)
      text = ' '.join([x for x in text.split() if x and x not in STOPWORDS])
      return text.strip()
  
  def array_to_string(arr):
      return '\n'.join(str(num) for num in arr)
  
  def matrix_to_string(matrix):
      return '\n'.join('\t'.join(str(num) for num in line) for line in matrix)
  