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GhPython vs Python: TypeErrorException from GH but not from Shell

I am using a library called py_openshowvar to communicate with a Kuka robot arm from grasshopper.
Everything works fine if I run the program from a command line python shell. However, when I run the same thing from GhPython, I get the following:
Not sure why I get the exceptions with GhPython but not when I run it outside the GH environment. The program still connects to the server and retrieves/sends the info I need, but I want to make sure and address this exception.
Thanks!

It is hard to tell you how to fix the error as you do not provide the code that triggers it, but in substance it comes from the fact that GHPython is IronPython (an implementation of Python based on .Net) whereas Python Shell is an implementation written in C.
The two implementations are similar but you sometimes hit a difference.
In your case the script is expecting a string or tuple but gets an IronPython.Runtime.Bytes.

Hmm, got bytes when expecting str looks like a unicode string vs byte string problem. You do no describe what are the versions of your CPython and GHPython, but you should know that Python 2 strings are byte strings while Python 3 ones are unicode strings.
If in Python 2 you can force a litteral string to be unicode by prepending it with u: u"foo" is a unicode string. You can also decode a byte string to its unicode version: b'ae\xe9\xe8'.decode('Latin1') is the unicode string u'aeéè'

Converting PySerial Code from Python 3 to 2.7

I'm trying to port a program written in Python 3.5 to 2.7, but it seems the addition of bytes objects in Python 3 changes how PySerial is implemented. Unfortunately, I cannot find any documentation for PySerial 2.x, so I would greatly appreciate help converting this code from PySerial 3 to 2:
import serial
ser = serial.Serial('COM6', 9600)
ser.write(bytes(chr(0x30), 'UTF-8'))
dataIn = ser.read(size=4)
Since the bytes object is just an alias for the str type in Python 2.x, I get the following error:
TypeError: str() takes at most 1 argument (2 given)
Does PySerial's write() method use a bytearray object as the parameter or does it use a string with another parameter for the encoding?
What datatype does ser.read(size=4) return?
Or better yet if someone has a link to the documentation...

Well, I had to literally use a time machine to find PySerial 2's documentation, which no longer exists, but now I can answer my own question:
ser.write() accepts a str or, indeed, a bytearray in Python 2.6+. A bytearray is probably better so I can specify the encoding if I want, since a str's encoding seems to depend on system settings. So my code is now:
ser.write(bytearray([0x30]))
Also, ser.read returns a str (or a bytes in Py2.6+).

how to convert Python 2 unicode() function into correct Python 3.x syntax

I enabled the compatibility check in my Python IDE and now I realize that the inherited Python 2.7 code has a lot of calls to unicode() which are not allowed in Python 3.x.
I looked at the docs of Python2 and found no hint how to upgrade:
I don't want to switch to Python3 now, but maybe in the future.
The code contains about 500 calls to unicode()
How to proceed?
Update
The comment of user vaultah to read the pyporting guide has received several upvotes.
My current solution is this (thanks to Peter Brittain):
from builtins import str
... I could not find this hint in the pyporting docs.....

As has already been pointed out in the comments, there is already advice on porting from 2 to 3.
Having recently had to port some of my own code from 2 to 3 and maintain compatibility for each for now, I wholeheartedly recommend using python-future, which provides a great tool to help update your code (futurize) as well as clear guidance for how to write cross-compatible code.
In your specific case, I would simply convert all calls to unicode to use str and then import str from builtins. Any IDE worth its salt these days will do that global search and replace in one operation.
Of course, that's the sort of thing futurize should catch too, if you just want to use automatic conversion (and to look for other potential issues in your code).

You can test whether there is such a function as unicode() in the version of Python that you're running. If not, you can create a unicode() alias for the str() function, which does in Python 3 what unicode() did in Python 2, as all strings are unicode in Python 3.
# Python 3 compatibility hack
try:
unicode('')
except NameError:
unicode = str
Note that a more complete port is probably a better idea; see the porting guide for details.

Short answer: Replace all unicode calls with str calls.
Long answer: In Python 3, Unicode was replaced with strings because of its abundance. The following solution should work if you are only using Python 3:
unicode = str
# the rest of your goes goes here
If you are using it with both Python 2 or Python 3, use this instead:
import sys
if sys.version_info.major == 3:
unicode = str
# the rest of your code goes here
The other way: run this in the command line
$ 2to3 package -w

First, as a strategy, I would take a small part of your program and try to port it. The number of unicode calls you are describing suggest to me that your application cares about string representations more than most and each use-case is often different.
The important consideration is that all strings are unicode in Python 3. If you are using the str type to store "bytes" (for example, if they are read from a file), then you should be aware that those will not be bytes in Python3 but will be unicode characters to begin with.
Let's look at a few cases.
First, if you do not have any non-ASCII characters at all and really are not using the Unicode character set, it is easy. Chances are you can simply change the unicode() function to str(). That will assure that any object passed as an argument is properly converted. However, it is wishful thinking to assume it's that easy.
Most likely, you'll need to look at the argument to unicode() to see what it is, and determine how to treat it.
For example, if you are reading UTF-8 characters from a file in Python 2 and converting them to Unicode your code would look like this:
data = open('somefile', 'r').read()
udata = unicode(data)
However, in Python3, read() returns Unicode data to begin with, and the unicode decoding must be specified when opening the file:
udata = open('somefile', 'r', encoding='UTF-8').read()
As you can see, transforming unicode() simply when porting may depend heavily on how and why the application is doing Unicode conversions, where the data has come from, and where it is going to.
Python3 brings greater clarity to string representations, which is welcome, but can make porting daunting. For example, Python3 has a proper bytes type, and you convert byte-data to unicode like this:
udata = bytedata.decode('UTF-8')
or convert Unicode data to character form using the opposite transform.
bytedata = udata.encode('UTF-8')
I hope this at least helps determine a strategy.

You can use six library which have text_type function (unicode in py2, str in py3):
from six import text_type

python 2.7 to 3.3 string encode/decode changes

I am just fixing a 2.7 script to 3.5 and ran into some decode/encode issues.
id = entry.attrib['{http://www.opengis.net/gml/3.2}id']
code = id.split('-')[2]
doc['code'] = (code + u"-area").decode('utf-8')
above is the 2.7 version that reads stuff from a xml file. What is the correct way of doing this in 3.3 since some encoding stuff was changed and 'str' object has no attribute 'decode' any more.
I have seen this also: .encode('UTF-8').decode('utf-8') do this have any effect ?

Python 3.X already holds unicode characters, so I think you do not need to use .decode('utf-8'). In the moment you need to store in someway/somewhere your doc['code'] then you can use .encode('utf-8') and then retrieve it through .decode('utf-8')

TypeError connecting to tweetstream -- Python 3.2

Apologies, sure this is simple:
New to Python and to Python interfaces with Twitter's streaming API, trying to use tweetstream on Python 3.2 to do so.
import tweetstream
stream = tweetstream.FilterStream(username = "myusername", password = "mypassword", track = bytes("oprah", encoding = "utf-8"))
for tweet in stream:
print(tweet)
Throws:
TypeError: sequence item 0: expected str instance, int found
I had encoded the 'track' argument because earlier attempts to pass a string threw,
TypeError: POST data should be bytes or an iterable of bytes. It cannot be str.
Thanks.

Your problem is you are using Python3 with a Python2 package.
See here for information on Python3 bytes:
http://docs.python.org/release/3.0.1/library/functions.html#bytes
Also this:
http://docs.python.org/whatsnew/2.6.html#pep-3112-byte-literals
In python3, this will send an array of bytes. However, _get_post_data function is expecting a string. The way strings are handled in python3 and python2 is totally different and the source of much frustration for those wishing to port to Python3.
Unless this package makes this compatible with Python3, you will need to use Python2. You could do it yourself of course, but considering any other package you will use will also be limited to using python2, I would recommend going that way.
Basically, in python 2.6/2.7, if you do
b = bytes('a')
print type(b)
you will get type str
In python 3, if you do
b = bytes('a')
print(type(b))
You will get type "bytearray"