Downloading from remote data source
Two epynomous methods are provided for downloading free data, from both Yahoo Finance (yahoo) and the Federal Reserve St. Louis (fred).
These methods take a string argument that represents the name of the desired data set to be downloaded.
These methods have default arguments. These defaults only apply when no argument is passed, otherwise the user is left with determining the correct name for the data of interest.
Yahoo
For the yahoo() method, the default data is the S&P 500 end-of-day daily prices. That symbol is named ^GSPC.
Yahoo! Finance has been immediately deprecated. Yahoo! substantially altered their API in late 2017 and this csv endpoint was retired.
FRED
The default data for the fred() method is CPIAUCNS, which represents the Consumer Price Index for All Urban Consumers data.