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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 catalog(self):
 """Create MOC from catalog of coordinates. This command requires that the Healpy and Astropy libraries be available. It attempts to load the given catalog, and merges it with the running MOC. The name of an ASCII catalog file should be given. The file should contain either "RA" and "Dec" columns (for ICRS coordinates) or "Lon" and "Lat" columns (for galactic coordinates). The MOC order and radius (in arcseconds) can be given with additional options. :: pymoctool --catalog coords.txt [order 12] [radius 3600] [unit (hour | deg | rad) (deg | rad)] [format commented_header] [inclusive] Units (if not specified) are assumed to be hours and degrees for ICRS coordinates and degrees for galactic coordinates. The format, if not specified (as an Astropy ASCII table format name) is assumed to be commented header, e.g.: :: # RA Dec 01:30:00 +45:00:00 22:30:00 +45:00:00 """


        from .catalog import catalog_to_moc, read_ascii_catalog

        filename = self.params.pop()
        order = 12
        radius = 3600
        unit = None
        format_ = 'commented_header'
        kwargs = {}

        while self.params:
            if self.params[-1] == 'order':
                self.params.pop()
                order = int(self.params.pop())
            elif self.params[-1] == 'radius':
                self.params.pop()
                radius = float(self.params.pop())
            elif self.params[-1] == 'unit':
                self.params.pop()
                unit_x = self.params.pop()
                unit_y = self.params.pop()
                unit = (unit_x, unit_y)
            elif self.params[-1] == 'format':
                self.params.pop()
                format_ = self.params.pop()
            elif self.params[-1] == 'inclusive':
                self.params.pop()
                kwargs['inclusive'] = True
            else:
                break

        coords = read_ascii_catalog(filename, format_=format_, unit=unit)
        catalog_moc = catalog_to_moc(coords, radius, order, **kwargs)

        if self.moc is None:
            self.moc = catalog_moc
        else:
            self.moc += catalog_moc