How to use the ogr.osr.SpatialReference function in ogr

def parse_geojson_crs(body):
    """Imports a coordinate reference system (CRS) from a GeoJSON tree."""
    crs_body = body.get("crs") or body.get("srs")
    crs_type = crs_body.get("type", "").upper()
    crs_opts = list(crs_body.get("properties").values())  # FIXME: no specific mapping of inputs, each is different
    crs = ogr.osr.SpatialReference()
    err = -1
    if crs_type == "EPSG":
        err = crs.ImportFromEPSG(*crs_opts)
    elif crs_type == "EPSGA":
        err = crs.ImportFromEPSGA(*crs_opts)
    elif crs_type == "ERM":
        err = crs.ImportFromERM(*crs_opts)
    elif crs_type == "ESRI":
        err = crs.ImportFromESRI(*crs_opts)
    elif crs_type == "USGS":
        err = crs.ImportFromUSGS(*crs_opts)
    elif crs_type == "PCI":
        err = crs.ImportFromPCI(*crs_opts)
    # add dirty hack for geojsons used in testbed15-d104
    elif crs_type == "NAME" and len(crs_opts) == 1 and ":EPSG:" in crs_opts[0]:
        err = crs.ImportFromEPSG(int(crs_opts[0].split(":")[-1]))

def mask(self, ar=None, nodata=0, scale=10):
        import ogr
        import gdal
        from osgeo.gdalconst import GDT_Byte
        import numpy as np
        import numpy.ma as ma

        """Return an numpy array with a hard mask to exclude areas outside of the place"""
        srs_in = ogr.osr.SpatialReference()
        srs_in.ImportFromEPSG(self.row['srid'])

        aa = self.aa(scale)

        image = aa.get_memimage(data_type=GDT_Byte)

        ogr_ds = ogr.GetDriverByName('Memory').CreateDataSource('/tmp/foo')
        lyr = ogr_ds.CreateLayer('place', aa.srs)

        geometry = ogr.CreateGeometryFromWkt(self.row['wkt'])
        geometry.AssignSpatialReference(srs_in)
        geometry.TransformTo(aa.srs)

        feature = ogr.Feature(lyr.GetLayerDefn())
        feature.SetGeometryDirectly(geometry)

def project(geom, from_epsg=900913, to_epsg=4326):
    # source: http://hackmap.blogspot.com/2008/03/ogr-python-projection.html
    to_srs = ogr.osr.SpatialReference()
    to_srs.ImportFromEPSG(to_epsg)

    from_srs = ogr.osr.SpatialReference()
    from_srs.ImportFromEPSG(from_epsg)

    ogr_geom = ogr.CreateGeometryFromWkb(geom.wkb)
    ogr_geom.AssignSpatialReference(from_srs)

    ogr_geom.TransformTo(to_srs)
    return loads(ogr_geom.ExportToWkb())

def get_srs(self):
        import ogr

        srs = ogr.osr.SpatialReference()
        srs.ImportFromWkt(self.get_srs_wkt())
        return srs

def project(geom, from_epsg=900913, to_epsg=4326):
    # source: http://hackmap.blogspot.com/2008/03/ogr-python-projection.html
    to_srs = ogr.osr.SpatialReference()
    to_srs.ImportFromEPSG(to_epsg)

    from_srs = ogr.osr.SpatialReference()
    from_srs.ImportFromEPSG(from_epsg)

    ogr_geom = ogr.CreateGeometryFromWkb(geom.wkb)
    ogr_geom.AssignSpatialReference(from_srs)

    ogr_geom.TransformTo(to_srs)
    return loads(ogr_geom.ExportToWkb())

# Sometimes the EPSG numbers come from the database as strings
        try:
            srs_spec = int(srs_spec)
        except:
            pass

        srs = ogr.osr.SpatialReference()

        if srs_spec is None and default is not None:
            return self._get_srs(default, None)
            # srs.ImportFromEPSG(default)  # Lat/Long in WGS84
        elif isinstance(srs_spec, int):
            srs.ImportFromEPSG(srs_spec)
        elif isinstance(srs_spec, basestring):
            srs.ImportFromWkt(srs_spec)
        elif isinstance(srs_spec, ogr.osr.SpatialReference):
            return srs_spec
        else:
            raise ValueError("Bad srs somewhere. Source={}, Default = {}"
                             .format(srs_spec, default))

        return srs

def get_transform(self, dest_srs=4326):
        """Get an ogr transform object to convert from the SRS of this
        partition to another."""
        import ogr
        import osr

        srs2 = ogr.osr.SpatialReference()
        srs2.ImportFromEPSG(dest_srs)
        transform = osr.CoordinateTransformation(self.get_srs(), srs2)

        return transform

def _get_srs(self, srs_spec=None, default=4326):

        srs = ogr.osr.SpatialReference()

        if srs_spec is None and default is not None:
            return self._get_srs(default, None)
            srs.ImportFromEPSG(default)  # Lat/Long in WGS84
        elif isinstance(srs_spec, int):
            srs.ImportFromEPSG(srs_spec)
        elif isinstance(srs_spec, basestring):
            srs.ImportFromWkt(srs_spec)
        elif isinstance(srs_spec, ogr.osr.SpatialReference):
            return srs_spec
        else:
            raise ValueError("Bad srs somewhere. Source={}, Default = {}".format(srs_spec, default))

        return srs