VisaIOError: VI_ERROR_RSRC_NFOUND (-1073807343): Insufficient location information or the requested device or resource is not present in the system - pyvisa

Question

I am running a code to connect Keithley multimeter to my laptop. I am using windows 10 and python 2.7. But when I try to run the code, this appears. Help me, i am very basic in programming and computer and I am in need of help. I have been searching for solution for days but to no avail , after I have fixed one error, another error pops up. this is the latest error. I hope after this one is solved i can use it . This is the message from iPython
runfile('C:/Users/user/Downloads/program (2).py',
wdir='C:/Users/user/Downloads') initializing Traceback (most recent
call last):
File "", line 1, in
runfile('C:/Users/user/Downloads/program (2).py', wdir='C:/Users/user/Downloads')
File
"C:\Users\user\Anaconda2\lib\site-packages\spyder\utils\site\sitecustomize.py",
line 710, in runfile
execfile(filename, namespace)
File
"C:\Users\user\Anaconda2\lib\site-packages\spyder\utils\site\sitecustomize.py",
line 86, in execfile
exec(compile(scripttext, filename, 'exec'), glob, loc)
File "C:/Users/user/Downloads/program (2).py", line 422, in
dmm = DMM()
File "C:/Users/user/Downloads/program (2).py", line 40, in init
self.A=self.rm.open_resource('ASRL3::INSTR')
File "C:\Users\user\Anaconda2\lib\pyvisa\highlevel.py", line 1656,
in open_resource
res.open(access_mode, open_timeout)
File "C:\Users\user\Anaconda2\lib\pyvisa\resources\resource.py",
line 209, in open
self.session, status = self._resource_manager.open_bare_resource(self._resource_name,
access_mode, open_timeout)
File "C:\Users\user\Anaconda2\lib\pyvisa\highlevel.py", line 1613,
in open_bare_resource
return self.visalib.open(self.session, resource_name, access_mode, open_timeout)
File "C:\Users\user\Anaconda2\lib\pyvisa\ctwrapper\functions.py",
line 1213, in open
ret = library.viOpen(session, resource_name, access_mode, open_timeout, byref(out_session))
File "C:\Users\user\Anaconda2\lib\pyvisa\ctwrapper\highlevel.py",
line 188, in _return_handler
raise errors.VisaIOError(ret_value)
VisaIOError: VI_ERROR_RSRC_NFOUND (-1073807343): Insufficient location
information or the requested device or resource is not present in the
system.