code: def insert_symbol(self, sname, skind, stype):
          
          self.table.append(SymbolTableEntry(sname, skind, stype))
          self.table_len = len(self.table)
          return self.table_len-1
docs: Inserts new symbol at the end of the symbol table.
             Returns symbol index
             sname - symbol name
             skind - symbol kind
             stype - symbol type