'Return True if the operand is a quiet NaN; otherwise return False.
>>> ExtendedContext.is_qnan(Decimal(\'2.50\'))
False
>>> ExtendedContext.is_qnan(Decimal(\'NaN\'))
True
>>> ExtendedContext.is_qnan(Decimal(\'sNaN\'))
False
>>> ExtendedContext.is_qnan(1)
False'

def is_qnan(self, a):

    a = _convert_other(a, raiseit=True)
    return a.is_qnan()
