public BigInteger Add(
BigInteger value)
{
if (this.sign == 0)
return value;
if (this.sign != value.sign)
{
if (value.sign == 0)
return this;
if (value.sign < 0)
return Subtract(value.Negate());
return value.Subtract(Negate());
}
return AddToMagnitude(value.magnitude);
}
