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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 get_collection(self, collection, filter=None, fields=None, page_size=None):
 """ Returns a specific collection from the asset service with the given collection endpoint. - filters such as "name=Vesuvius" following GEL spec - fields such as "uri,description" comma delimited - page_size such as "100" (the default) """

        params = {}
        if filter:
            params['filter'] = filter
        if fields:
            params['fields'] = fields
        if page_size:
            params['pageSize'] = page_size

        uri = self.uri + '/v1' + collection
        return self.service._get(uri, params=params)