def copy(self, newdata=None):
if newdata is None:<EOL><INDENT>newdata = self.data.copy()<EOL><DEDENT>return self.__class__(<EOL>self.molecule, self.origin.copy(), self.axes.copy(),<EOL>self.nrep.copy(), newdata, self.subtitle, self.nuclear_charges<EOL>)<EOL>
Return a copy of the cube with optionally new data.