I would like to extract keywords from the column df[“description”], such as “apple” and “banana”, and append it under the list output, I tried:

def kw(df):
    output = []
    apple = np.NaN

    if (df['description'].str.contains('apple', na = False)):
        output.append(output)    
   
    if (df['description'].str.contains('banana', na = False)):
        output.append(output)

    return output

df['kw'] = df.apply(kw)

but it caught the but caught the error AttributeError: 'str' object has no attribute 'str'