def to_python(self, value):
        value = super(BBoxField, self).to_python(value)
        if not value:
            return -180.0,-90.0,180.0,90.0

        try:
            lx, ly, ux, uy = value.split(',')
            if self.localize:
                lx = float(sanitize_separators(lx))
                ly = float(sanitize_separators(ly))
                ux = float(sanitize_separators(ux))
                uy = float(sanitize_separators(uy))

                if uy < ly or ux < lx:
                    raise ValidationError("BBoxes must be in lower-left(x,y), upper-right(x,y) order")
        except (__HOLE__, TypeError):
            raise ValidationError("BBoxes must be four floating point values separated by commas")

        lx = float(sanitize_separators(lx))
        ly = float(sanitize_separators(ly))
        ux = float(sanitize_separators(ux))
        uy = float(sanitize_separators(uy))
        return lx, ly, ux, uy
dataset/ETHPy150Open hydroshare/hydroshare2/ga_resources/utils.py/BBoxField.to_python