getRecordIndex = function(map, recordKey) {
		var hashedKey = hashKey(recordKey); // Casts key to unique string (unless already string or number)
		if (hashedKey === false) {
			// We have to iterate through our Map structure because `recordKey` is non-primitive and not extensible
			return getRecordIndexSlow(map, recordKey);
		}
		var recordIndex = map._table[hashedKey]; // O(1) access to record
		return recordIndex !== undefined ? recordIndex : false;
	}
getRecordIndex()
Function that given a Map and a key of `any` type, returns an index number that coorelates with a record found in `this._keys[index]` and `this._values[index]`
@param {Map} map - Map structure 
@param {string|number|function|object} recordKey - Record key to normalize to string accessor for hash map
@returns {number|false} - Returns either a index to access map._keys and map._values, or false if not found