**Use case**
Some program left garbage in terminal.

**Describe the solution you'd like**
Subset of what `reset` command does.
external_tables_arguments.back().emplace_back(arg);
                    ++arg_num;
                    arg = argv[arg_num];
                    external_tables_arguments.back().emplace_back(arg);
                }
                else
                    break;
            }
            else
            
                in_external_group = false;
                /// Parameter arg after underline.
                if (start
                
                    c param_continuation = arg + strlen("--param_");
                    c equal_pos = strchr(param_continuation, '=');
                    if (equal_pos == param_continuation)
                        throw Exception("Parameter name cannot be empty", ErrorCodes::BAD_ARGUMENTS);
                    if (equal_pos)
                    
                        /// param_name=value
                        query_parameteram_continuation, equal_pos), String(equal_pos + 1));
                    }
                    else
                    
                        /// param_name value
                        ++arg_num;
                        arg = argv[arg_num];
                        query_parameteram_continuation), String(arg));