import pandas as pd 

pc = pd.read_csv(r"<path to main file>")
hm = pd.read_csv(r"<path to file we want to join>")

join = pd.merge(left=pc,right=hm,how='left', indicator=True, left_on='person_identifier', right_on='person_identifier')

join.head()

join.to_csv(r"<path to destination>")

d4705d200ae0c1f9afeb641e3b0d194df711e406
<mask token>

<mask token>
join.head()
join.to_csv('<path to destination>')

<mask token>
pc = pd.read_csv('<path to main file>')
hm = pd.read_csv('<path to file we want to join>')
join = pd.merge(left=pc, right=hm, how='left', indicator=True, left_on=
    'person_identifier', right_on='person_identifier')
join.head()
join.to_csv('<path to destination>')

import pandas as pd
pc = pd.read_csv('<path to main file>')
hm = pd.read_csv('<path to file we want to join>')
join = pd.merge(left=pc, right=hm, how='left', indicator=True, left_on=
    'person_identifier', right_on='person_identifier')
join.head()
join.to_csv('<path to destination>')

import pandas as pd 

pc = pd.read_csv(r"<path to main file>")
hm = pd.read_csv(r"<path to file we want to join>")

join = pd.merge(left=pc,right=hm,how='left', indicator=True, left_on='person_identifier', right_on='person_identifier')

join.head()

join.to_csv(r"<path to destination>")
