code: def detect_encoding(filename):
      
      try:
          with open(filename, 'rb') as input_file:
              from lib2to3.pgen2 import tokenize as lib2to3_tokenize
              encoding = lib2to3_tokenize.detect_encoding(input_file.readline)[0]
  
              # Check for correctness of encoding.
              with open_with_encoding(filename, encoding) as input_file:
                  input_file.read()
  
          return encoding
      except (SyntaxError, LookupError, UnicodeDecodeError):
          return 'latin-1'
docs: Return file encoding.