code: def create_index(self, table, field, unique=False, ascending=True):
          
          
          
          if unique: u = "unique "
          else: u = ""
          if ascending: a = "asc"
          else: a = "desc"
          sql  = "create "+u+"index index_"+table+"_"+field+" "
          sql += "on "+table+"("+field+" "+a+")"
          self._cur.execute(sql)
          self._con.commit()
docs: Creates a table index.
          
          Creates an index on the given table,
          on the given field with unique values enforced or not,
          in ascending or descending order.