The P/E ratio (price-to-earnings ratio) of a stock (also called its "P/E", or simply "multiple")
is a measure of the price paid for a share relative to the annual net income or profit earned by
the firm per share.
Important: This measure should not be used in production code if used with Compustat data,
since Compustat data may not lag accounting data to account for delays in release. Thus it may
contain data that was unavailable at the time.
TODO: verify how the info release date from compustat has been manipulated (should be
fixed/offset in compustat class, not this)