.IsValidPredictsData: Check if a PREDICTS extract is valid.
Description
A small set of basic checks to ensure that a PREDICTS extract is valid.
These include checking the object is a dataframe, checking all the columns
are valid, and checking that we have a nonzero row count.
Usage
.IsValidPredictsData(df)
Value
Boolean, TRUE if the dataframe is valid, FALSE if not.