Given a table as a parameter, this built-in function will output a table that indicates whether the input table is real and full of values or whether it is the result of an operation that produced nothing, which is different to producing an empty table.
A table with a single row and a single column called
An instruction that generates and tests for an undefined table. The reason it is undefined is because the body of the foreach is never executed. The script output is column Value with a cell containing the number one.
An instruction that generates and tests for an defined table. The script output is column Value with a cell containing the number zero.
Only works for @tables not $tables.