Python node 2:1 and lost python connection


I  use python 2:1 script node in forkflow for join two tables according some conditions. But in code when I use for example for loop statement and execute the script I recieve error mesage connection to python lost. But when I use default statemet for node like:

output_table = input_table_1.join(input_table_2, how='outer', lsuffix=' (left)', rsuffix=' (right)')


Execution of node run correctly.


Thans for help.