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# ein.py - functions for handling EINs
#
# Copyright (C) 2013 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""EIN (U.S. Employer Identification Number).
The Employer Identification Number, also known as Federal Employer
Identification Number (FEIN), is used to identify a business entity in the
United States. It is issued to anyone that has to pay withholding taxes on
employees.
>>> validate('91-1144442')
'911144442'
>>> get_campus('04-2103594') == 'Brookhaven'
True
>>> validate('911-14-4442') # dash in the wrong place
Traceback (most recent call last):
...
InvalidFormat: ...
>>> validate('07-1144442') # wrong prefix
Traceback (most recent call last):
...
InvalidComponent: ...
>>> format('042103594')
'04-2103594'
>>> format('123') # unknown formatting is left alone
'123'
"""
import re
from stdnum.exceptions import *
from stdnum.util import clean
# regular expression for matching EINs
_ein_re = re.compile(r'^(?P<area>[0-9]{2})-?(?P<group>[0-9]{7})$')
def compact(number):
"""Convert the number to the minimal representation. This strips the
number of any valid separators and removes surrounding whitespace."""
return clean(number, '-').strip()
def get_campus(number):
"""Determine the Campus or other location that issued the EIN."""
from stdnum import numdb
number = compact(number)
results = numdb.get('us/ein').info(number)[0][1]
if not results:
raise InvalidComponent()
return results['campus']
def validate(number):
"""Check if the number is a valid EIN. This checks the length, groups and
formatting if it is present."""
match = _ein_re.search(clean(number, '').strip())
if not match:
raise InvalidFormat()
get_campus(number) # raises exception for unknown campus
return compact(number)
def is_valid(number):
"""Check if the number is a valid EIN."""
try:
return bool(validate(number))
except ValidationError:
return False
def format(number):
"""Reformat the number to the standard presentation format."""
if len(number) == 9:
number = number[:2] + '-' + number[2:]
return number
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