Exclude a specified list of columns

[txnelson]

I would like to see a new function that excludes a specified list of columns

obj << exclude columns( <{column 1, column 2, ......}> | <[ column #, column # ....]>)

Examples:

dt << exclude columns( {:A, :B } );
dt << exclude columns( index( 5, 7 ) );
dt << exclude columns( dt << get selected columns );