public Eq dpart()
{
if (this.operat == "d")
{
return(this);
}
else
{
if (operand2 != null)
{
if (operand2.dpart() == null)
{
return(operand1.dpart());
}
return(operand2.dpart());
}
else if (operand1 != null)
{
return(operand1.dpart());
}
else
{
return(null);
}
}
}
