"cyclient.node.select_from_file" returns UnboundLocalError

[kozo2]

Cytoscape: 3.7.1

CyRest: 3.8.0

Java:

java -version
openjdk version "1.8.0_222"
OpenJDK Runtime Environment Corretto-8.222.10.1 (build 1.8.0_222-b10)
OpenJDK 64-Bit Server VM Corretto-8.222.10.1 (build 25.222-b10, mixed mode)

Code:

wget http://nrnb.org/data/BasicDataVizDemo.cys

from py2cytoscape import cyrest
cytoscape=cyrest.cyclient()
cytoscape.session.open(session_file="./BasicDataVizDemo.cys")
cytoscape.node.select_from_file(afile="./node_names.txt")

error:

---------------------------------------------------------------------------
UnboundLocalError                         Traceback (most recent call last)
<ipython-input-5-3b06a5138042> in <module>
----> 1 cytoscape.node.select_from_file(afile="./node_names.txt")

~/miniconda3/lib/python3.7/site-packages/py2cytoscape/cyrest/node.py in select_from_file(self, afile, verbose)
    222         :param verbose: print more
    223         """
--> 224         network=check_network(self,network,verbose=verbose)
    225         PARAMS=set_param(["file"],[afile])
    226         response=api(url=self.__url+"/select from file", PARAMS=PARAMS, method="POST", verbose=verbose)

UnboundLocalError: local variable 'network' referenced before assignment