Given a str as a path the symbol .json file or a symbol, returns a Symbol object.

def _load_sym(sym, logger=logging):
    """Given a str as a path the symbol .json file or a symbol, returns a Symbol object."""
    if isinstance(sym, str):  # sym is a symbol file path
        cur_path = os.path.dirname(os.path.realpath(__file__))
        symbol_file_path = os.path.join(cur_path, sym)
        logger.info('Loading symbol from file %s' % symbol_file_path)
        return sym_load(symbol_file_path)
    elif isinstance(sym, Symbol):
        return sym
    else:
        raise ValueError('_load_sym only accepts Symbol or path to the symbol file,'
                         ' while received type %s' % str(type(sym)))