'Return the sum of the two operands.
>>> ExtendedContext.add(Decimal(\'12\'), Decimal(\'7.00\'))
Decimal(\'19.00\')
>>> ExtendedContext.add(Decimal(\'1E+2\'), Decimal(\'1.01E+4\'))
Decimal(\'1.02E+4\')
>>> ExtendedContext.add(1, Decimal(2))
Decimal(\'3\')
>>> ExtendedContext.add(Decimal(8), 5)
Decimal(\'13\')
>>> ExtendedContext.add(5, 5)
Decimal(\'10\')'

def add(self, a, b):

    a = _convert_other(a, raiseit=True)
    r = a.__add__(b, context=self)
    if (r is NotImplemented):
        raise TypeError(('Unable    to    convert    %s    to    Decimal' % b))
    else:
        return r
