How to apply if else conditions to assign values to new column using lambda

How to apply if else conditions to assign values to new column using lambda

def func(df1,df2,by,suffix):
    df1 = df1.assign(found_on=lambda x: 'Y')
    df2 = df2.assign(found_on=lambda x: 'Y')
    df1 = df1.merge(df2, how='outer', on=by, suffixes=suffix)
    col1= 'found_on' + suffix[0]
    col2='found_on' + suffix[1]
    print(col1)
    df1 = df1.assign(delta_info=lambda x:"on both" if (df1[col1].notna() and df1[col2].notna()) else (("on" + suffix[1]) if (df1[col1].isna() and df1[col2].notna()) else (("on" + suffix[0]) if (df1[col1].notna() and df1[col2].isna()) else "review")))
    print(df1)