human
Solve the following python programming problem given the following code:
def bitpack(self, arrs, indices) : 
    'Pack an array of integers into a byte based on idx
        for example bitpack((arr1, arr2), (0,3), (3,8)) packs the integers
        arr1 and arr2 into a byte, using the first three bits
        of arr1, and the last five bits of arr2. 
        ' 
    def keep_bits(arr, low, high) : 
        ' Keep only the bits on the interval [low, high) ' 
        return np.bitwise_and (np.bitwise_and (arr, ((2 ** high) - 1)), (~ ((2 ** low) - 1))).astype (np.uint8) 
first_bit_idx = 0 
    packed = np.zeros_like (arrs [0]) 
    for (arr, (low, high)) in zip (arrs, indices) : 
        if (low > first_bit_idx) : 
            packed += np.right_shift (keep_bits (low, low, high), (low - first_bit_idx)) 
else : 
            packed += np.left_shift (keep_bits (arr, low, high), (first_bit_idx - low)) 
first_bit_idx += (high - low) 
        if (first_bit_idx > 8) : 
            raise laspy.util.LaspyException ('Invalid Data: Packed Length is Greater than allowed.') 
return list (packed) 

    
    

    Fix the buggy line: packed += np.right_shift (keep_bits (low, low, high), (low - first_bit_idx))
assistant
#Here is Python program to fix the buggy line: packed += np.

packed += np.right_shift (keep_bits (arr, low, high), (low - first_bit_idx))