'Return True if the operand is finite; otherwise return False.
A Decimal instance is considered finite if it is neither
infinite nor a NaN.
>>> ExtendedContext.is_finite(Decimal(\'2.50\'))
True
>>> ExtendedContext.is_finite(Decimal(\'-0.3\'))
True
>>> ExtendedContext.is_finite(Decimal(\'0\'))
True
>>> ExtendedContext.is_finite(Decimal(\'Inf\'))
False
>>> ExtendedContext.is_finite(Decimal(\'NaN\'))
False
>>> ExtendedContext.is_finite(1)
True'

def is_finite(self, a):

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