class Calculator(object):
    def __init__(self):
                 self.object = object
    def power(self, a,b):
                 self.a = a
                 self.b = b
                 if self.a>=0 and self.b >=0:
                    return (a**b)
                 else:
                    e = "n and p should be non-negative"
                    return e
