Returns a series of columns of the data frame indexed by the column keys, which contains those series whose values are convertible to `'T`, and with missing values where the conversion fails. If you want to get numeric columns, you can use a simpler `numericCols` function instead. Note that this function typically requires a type annotation. This can be specified in various ways, for example by annotating the result value: let (res:Series<_, Series<_, string>>) = frame |> getCols Here, the annotation on the values of the nested series specifies that we want to get columns containing `string` values. [category:Accessing frame data and lookup]

public static Series<C, Series<R, T>> GetColumns<R, C, T>(
	Frame<R, C> frame
)