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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find_domain(session, name):
 """Find a domain. Find a domain by its domain name using the given `session`. When the domain does not exist the function will return `None`. :param session: database session :param name: name of the domain to find :returns: a domain object; `None` when the domain does not exist """

    domain = session.query(Domain). \
        filter(Domain.domain == name).first()

    return domain