old_contents: CACHE = {}
  DATABASES = {
      'full': 'corpora/en.txt',
      'min': 'corpora/en_min.txt',
  }
  
  
  class Corpus:
  
      def __init__(self, filepath):
          if filepath in CACHE:
              self.freq_lookup = CACHE[filepath]
          else:
              self.freq_lookup = {}
              with open(filepath, 'r') as file:
                  for line in file:
                      word, freq = line.split(' ')
                      self.freq_lookup[word] = int(freq)
              CACHE[filepath] = self.freq_lookup
  
      def is_known(self, word):
          return word in self.freq_lookup
  
      def freq(self, word):
          return self.freq_lookup.get(word, 0)
  
new_contents: CACHE = {}
  DATABASES = {
      'full': 'corpora/en.txt',
      'min': 'corpora/en_min.txt',
  }
  
  
  class Corpus:
  
      def __init__(self, filepath):
          if filepath in CACHE:
              self.freq_lookup = CACHE[filepath]
          else:
              self.freq_lookup = {}
              with open(filepath, 'r') as file:
                  for line in file:
                      word, freq = line.split(' ')
                      self.freq_lookup[word] = int(freq)
              CACHE[filepath] = self.freq_lookup
  
      def freq(self, word):
          return self.freq_lookup.get(word, 0)
  
subject: remove unused method