python fillna with mode

cateogry_columns=df.select_dtypes(include=['object']).columns.tolist()
integer_columns=df.select_dtypes(include=['int64','float64']).columns.tolist()

for column in df:
    if df[column].isnull().any():
        if(column in cateogry_columns):
            df[column]=df[column].fillna(df[column].mode()[0])
        else:
            df[column]=df[column].fillna(df[column].mean)

data['Native Country'] = data['Native Country'].fillna(data['Native Country'].mode()[0])