Python How to check presence of a column in dataframe by it's name or number

I have written a function which asks a user for column name (ex. 'Age') or column number (0, 1, ... or -1, -2, ...) and returns it if exists. I would like to know if my solution can be improved in terms of code design.

To clarify, I need this piece of code for another function which calculates Shannon Entropy on the dataframes for which label-column should be chosen manually.

import pandas as pd

df = pd.DataFrame({'A': [1,2,3], 'B':['a', 'b', 'c']})

def read(df):
    while True:
        column = input("Please, enter column name or number:") 
        if column.lstrip('-').isdecimal():
            if (-df.shape[1] > int(column)) or (int(column) >= df.shape[1]):
                print('Such column does not exist. Please, try again. \n')
                continue
            else:
                return df.iloc[:, int(column)]
        elif column not in df.columns:
            print('Such column does not exist. Please, try again. \n')
            continue
        else:
            return df.loc[:, column]
    return data[column]

read(df)