Python's argeparse using same option multiple times, but put those options in same list

In Python's argparse, using the same option multiple times puts those arguments in different lists. But I want those arguments on the same list.

The result I have got is:

# only the input portion
[
    [input1, input2],
    [input3, input4, input5],
    [input6]
]

My Code:

# myScript.py
import argparse
parser=argparse.ArgumentParser()
parser.add_argument('-i', action='append', nargs='+')
parser.add_argument('-o', action='append', nargs='*')
args = parser.parse_args()

Executing the code:

myScript.py -i input1 input2 -o output1 -i input3 input4 input5 -o output2 -i input6

The result I want is:

[
    input1, 
    input2, 
    input3, 
    input4, 
    input5,
    input6
]

To get those arguments in the same list[], we have to use action="extend" instead of action="append" in our code. So it doesn't matter how many time we use the option, we will get those arguments in the same single list.

[
    input1, 
    input2, 
    input3, 
    input4, 
    input5,
    input6
]

That means the code will be something like:

# myScript.py
import argparse
parser=argparse.ArgumentParser()
parser.add_argument('-i', action='extend', nargs='+')
parser.add_argument('-o', action='append', nargs='*')
args = parser.parse_args()