A set of zero or more CBI receivers.

Input Format:

A set of one or more of:

rx0 rx1 rx2 rx3 rx4 rx5 rx6 rx7 rx8 rx9 rx10 rx11 rx12

Where rx stands for receiver, and the trailing numbers are receiver numbers.

Examples:

 print $Receivers(rx2+rx10)
 -> rx2+rx10

 # Print all receiver names except those of receivers 3, 4 and 6.

 print $Receivers(all-rx3-rx4-rx6)
 -> rx0+rx1+rx2+rx5+rx7+rx8+rx9+rx10+rx11+rx12