code: def paddingLength(str_len, blocksize=AES_blocksize):
    ''' Function to calculate the length of the required padding
    Input: (int) str_len   - String length of the text 
           (int) blocksize - block size of the algorithm    
    Returns: (int) number of required pad bytes for string of size.'''
    assert 0 < blocksize < 255, 'blocksize must be between 0 and 255'
    assert str_len > 0 , 'string length should be non-negative'
    
    'If the last block is already full, append an extra block of padding'
    pad_len = blocksize - (str_len % blocksize)
    
    return pad_lef paddingLength(str_len, blocksize=AES_blocksize):
    ''' Function to calculate the length of the required padding
    Input: (int) str_len   - String length of the text 
           (int) blocksize - block size of the algorithm    
    Returns: (int) number of required pad bytes for string of size.'''
    assert 0 < blocksize < 255, 'blocksize must be between 0 and 255'
    assert str_len > 0 , 'string length should be non-negative'
    
    'If the last block is already full, append an extra block of padding'
    pad_len = blocksize - (str_len % blocksize)
    
    return pad_len
docs: Function to calculate the length of the required padding
    Input: (int) str_len   - String length of the text 
           (int) blocksize - block size of the algorithm    
    Returns: (int) number of required pad bytes for string of size.