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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 fetch(self, endpoint_name, identifier_input, query_params=None):
 """Calls this instance's request_client's post method with the specified component endpoint Args: - endpoint_name (str) - The endpoint to call like "property/value". - identifier_input - One or more identifiers to request data for. An identifier can be in one of these forms: - A list of property identifier dicts: - A property identifier dict can contain the following keys: (address, zipcode, unit, city, state, slug, meta). One of 'address' or 'slug' is required. Ex: [{"address": "82 County Line Rd", "zipcode": "72173", "meta": "some ID"}] A slug is a URL-safe string that identifies a property. These are obtained from HouseCanary. Ex: [{"slug": "123-Example-St-San-Francisco-CA-94105"}] - A list of dicts representing a block: - A block identifier dict can contain the following keys: (block_id, num_bins, property_type, meta). 'block_id' is required. Ex: [{"block_id": "060750615003005", "meta": "some ID"}] - A list of dicts representing a zipcode: Ex: [{"zipcode": "90274", "meta": "some ID"}] - A list of dicts representing an MSA: Ex: [{"msa": "41860", "meta": "some ID"}] The "meta" field is always optional. Returns: A Response object, or the output of a custom OutputGenerator if one was specified in the constructor. """


        endpoint_url = constants.URL_PREFIX + "/" + self._version + "/" + endpoint_name

        if query_params is None:
            query_params = {}

        if len(identifier_input) == 1:
            # If only one identifier specified, use a GET request
            query_params.update(identifier_input[0])
            return self._request_client.get(endpoint_url, query_params)

        # when more than one address, use a POST request
        return self._request_client.post(endpoint_url, identifier_input, query_params)