'Return True if the operand is a normal number;
otherwise return False.
>>> c = ExtendedContext.copy()
>>> c.Emin = -999
>>> c.Emax = 999
>>> c.is_normal(Decimal(\'2.50\'))
True
>>> c.is_normal(Decimal(\'0.1E-999\'))
False
>>> c.is_normal(Decimal(\'0.00\'))
False
>>> c.is_normal(Decimal(\'-Inf\'))
False
>>> c.is_normal(Decimal(\'NaN\'))
False
>>> c.is_normal(1)
True'

def is_normal(self, a):

    a = _convert_other(a, raiseit=True)
    return a.is_normal(context=self)
