'Lookup a single domain
:param domain_name: The name of the domain to look up
:type domain_name: str
:return: Domain object, or None if the domain isn\'t found
:rtype: :class:`boto.cloudsearch.domain.Domain`'

def lookup(self, domain_name):

    domains = self.list_domains(domain_names=[domain_name])
    if (len(domains) > 0):
        return domains[0]
