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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fsto(self):
 """sto operation. """

        a = float(self.tmpopslist.pop())
        var = self.opslist.pop()
        if isinstance(var, basestring):
            self.variables.update({var: a})
            return a
        else:
            print("Can only sto into a variable.")
            return 'ERROR'