docs: def is_text_file(filepath, blocksize=2**14):
      """ Uses heuristics to guess whether the given file is text or binary,
          by reading a single block of bytes from the file.
          If more than some abound of the chars in the block are non-text, or there
          are NUL ('\x00') bytes in the block, assume this is a binary file.
      """
      with open(filepath, "rb") as fileobj:
          block = fileobj.read(blocksize)
          if b'\x00' in block:
              # Files with null bytes are binary
              return False
          elif not block:
              # an empty file is considered a valid text file
              return True
  
          # Use translate's 'deletechars' argument to efficiently remove all
          # occurrences of _text_characters from the block
          nontext = block.translate(None, _text_characters)
          return float(len(nontext)) / len(block) <= 0.30