def col2sql_gen(col, default_table=None, table_is_esc=False):

    '''Converts old-style (tuple-based) columns to sql_gen-compatible values.

    @param table_is_esc If False, assumes any table name is not escaped or that

        re-escaping it will produce the same value.

    '''

    if isinstance(col, Col): return col # already in sql_gen form

    table = default_table

    if isinstance(col, tuple): table, col = col

    return Col(col, table2sql_gen(table, table_is_esc))

def value2sql_gen(value, default_table=None, table_is_esc=False,

    assume_col=False):

    '''Converts old-style (tuple-based) values to sql_gen-compatible values.

    @param table_is_esc If False, assumes any table name is not escaped or that

        re-escaping it will produce the same value.

    '''

    if isinstance(value, Code): return value # already in sql_gen form

    is_tuple = isinstance(value, tuple)

    if is_tuple and len(value) == 1: return Literal(value[0])

    if is_tuple or (assume_col and util.is_str(value)):

        return col2sql_gen(value, default_table, table_is_esc)

    else: return Literal(value)