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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 twotheta(self) -> ErrorValue: """Calculate the two-theta array"""

        row, column = np.ogrid[0:self.shape[0], 0:self.shape[1]]
        rho = (((self.header.beamcentery - row) * self.header.pixelsizey) ** 2 +
               ((self.header.beamcenterx - column) * self.header.pixelsizex) ** 2) ** 0.5
        assert isinstance(self.header.pixelsizex, ErrorValue)
        assert isinstance(self.header.pixelsizey, ErrorValue)
        assert isinstance(rho, ErrorValue)
        return (rho / self.header.distance).arctan()