how to join collection from mongodb using python

Question

I have 3 collections of 'Demo' cluster:
want to join all columns from these 3 tables.
as
data

{
"email":"jhelliar0@techcrunch.com",
"first_name":"Silvanus",
"last_name":"Spikins",
"mobile":"5279757399",
"car_model":"2500",
"car_color":"Orange",
"company_name":"Fanoodle",
"Desiganation":"Recruiter",
"country":"Georgia",
"city":"Marneuli"
}

Tables are:
emp_login

{
"_id":"$oid":"5e9435ff61a03e23fc7bdb64"},
"id":"1",
"email":"jhelliar0@techcrunch.com",
"password":"diOIE0qd3j"
}

employee

{
"_id":"$oid":"5e940eda61a03e23fc7bd392"},
"email":"jhelliar0@techcrunch.com",
"first_name":"Silvanus",
"last_name":"Spikins",
"mobile":"5279757399",
"car_model":"2500",
"car_color":"Orange"
}

company

{
"_id":"$oid":"5e940eb161a03e23fc7bcfa9"},
"email":"jhelliar0@techcrunch.com",
"company_name":"Fanoodle",
"Desiganation":"Recruiter",
"country":"Georgia",
"city":"Marneuli"
}

use email and password for login from emp_login cluster and after that join all related data from these clusters as shows above in data table