Python TypeError: 'function' object is not subscriptable

Question

What is meaning of the error and where is the mistake? I got the TypeError: 'function' object is not subscriptable for the following line:

row = random.choice(get_the_valid_locations[-2])

here is the get_the_valid_locations function:

def get_the_valid_locations(board):
        valid_locations = []
        for col in range(COLS_OF_BOARD):
            for row in range(ROWS_OF_BOARD):
                if available_square(board, row, col):
                    valid_locations.extend([row, col])
        return valid_locations

get_the_valid_locations[-2] is an int (I checked).

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Answer 1

The line that gives the error has a small mistake.
Now you try to take the second to last element of a function, but you I think you to give -2 as an argument to the function.
In that case the line should be:

row = random.choice(get_the_valid_locations(-2))

Then row will contain a random element from the output of your function.

EDIT
A comment (credits: buran) noted that the function requires a 2d array, in that case I think you mean well, but implement it wrong. You want the output to be an array of colums and an array of rows. Your statement would be used to choose a random value of the rows returned by the functions.
You could do it like this:

def get_the_valid_locations(board):
    valid_rows = []
    valid_columns = []
    for col in range(COLS_OF_BOARD):
        for row in range(ROWS_OF_BOARD):
            if available_square(board, row, col):
                valid_rows.append(row)
                valid_columns.append(col)
    return [valid_rows, valid_columns]

usage:

randomRow = random.choice(get_the_valid_locations(board)[0])

or

randomColumn = random.choice(get_the_valid_locations(board)[1])

Note: if you just want a random position on the `board` object, your code is correct, but your call should be:

row = random.choice(get_the_valid_locations(board))