def get_srid(crs):
    """Returns the SRID for the provided CRS definition
        The CRS can be defined in the following formats
        - urn:ogc:def:crs:EPSG::4326
        - EPSG:4326
        - 4326
       """

    if ':' in crs:
        crs = crs.split(':')
        srid = crs[len(crs)-1]
    else:
       srid = crs

    return int(srid)