1*ac2a7c1bSSadaf Ebrahimi# sets are represented as a 2*ac2a7c1bSSadaf Ebrahimi# mapping where each key is 3*ac2a7c1bSSadaf Ebrahimi# associated with the empty string 4*ac2a7c1bSSadaf Ebrahimi--- !!set 5*ac2a7c1bSSadaf Ebrahimi? Mark McGwire 6*ac2a7c1bSSadaf Ebrahimi? Sammy Sosa 7*ac2a7c1bSSadaf Ebrahimi? Ken Griff 8