calculating duration between two time columns

Question

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I have entry and exit time and I want to derive the total duration in seconds . I first converted it into date time and then made separate columns for entry and exit time using this code

import datetime as dt
from datetime import datetime
df["Entry Date Time"] = pd.to_datetime(df["Entry Date    Time"])
df["Exit"] = pd.to_datetime(df["Exit"])
df["EXIT_TIME"] = df["Exit"].apply(lambda x : x.time()) 
df["ENTRY_TIME"] = df["Entry Date Time"].apply(lambda x   : x.time()) 

Now I want to know the duration I tried doing this:

df["diff"] = df["EXIT_TIME"] - df["ENTRY_TIME"]

but it raises the error:

"unsupported operand type(s) for -: 'datetime.time' and 'datetime.time'"

How do I calculate the total duration for each row?