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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 eval(self, expression, vm='python'):
 """Evaluate an expression against the table columns. Parameters expression : string Expression to evaluate. vm : {'numexpr', 'python'} Virtual machine to use. Returns ------- result : ndarray """


        if vm == 'numexpr':
            import numexpr as ne
            return ne.evaluate(expression, local_dict=self)
        else:
            if PY2:
                # locals must be a mapping
                m = {k: self[k] for k in self.dtype.names}
            else:
                m = self
            return eval(expression, dict(), m)