public override bool Equals(Object o)
{
if (this == o)
{
return(true);
}
if ((o == null) || !(o is BinarySentence))
{
return(false);
}
BinarySentence bs = (BinarySentence)o;
return((bs.getOperator().Equals(getOperator())) &&
(bs.getFirst().Equals(first)) && (bs.getSecond()
.Equals(second)));
}