input: Write a function to read a text file and return the 10 most frequent words.
  assert most_frequent_words('text.txt') == ['the', 'of', 'and', 'to', 'a', 'in', 'is', 'it', 'you', 'that']
  assert most_frequent_words('another_text.txt') == ['this', 'is', 'a', 'test', 'of', 'the', 'function', 'to', 'check', 'frequency']
  assert most_frequent_words('empty.txt') == []
output: def most_frequent_words(filename):
      from collections import Counter
      import re
      
      with open(filename, 'r') as file:
          text = file.read().lower()
      
      words = re.findall(r'\b\w+\b', text)
      word_counts = Counter(words)
      
      most_common_words = [word for word, _ in word_counts.most_common(10)]
      
      return most_common_words