def set_crs(gdf, crs):
        """
        Set CRS in GeoDataFrame when current projection is not defined.
        Parameters
        ----------
        gdf : geopandas.GeoDataFrame
            the geodataframe to set the projection
        Returns
        -------
        gdf : geopandas.GeoDataFrame
            the geodataframe with the projection defined """
        gdf = gdf.set_crs(crs)
        
        return gdf