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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 _convert_latitude(self, latitude):
 """Convert from latitude to the y position in overall map."""

        return int((180 - (180 / pi * log(tan(
            pi / 4 + latitude * pi / 360)))) * (2 ** self._zoom) * self._size / 360)