Python Script locked for debug in VS 2015
<p>I'm doing the nucleai courses. Exercises are based on python scripts and I'm using Visual Studio 2015. At some point, we have to use the library nltk. I was trying to debug some code I'm calling (I have the source) and something really weird happens: breakpoints work, but I can't use F10 to jump line to line. It just skips all the script. I can debug without any problem any of my scripts but not those within the library.
So my question is: is there any option to "unlock" the script so I can debug line by line? 
I'm new with python and I can't find anything similar on google. I'm posting the code in case something is relevant. 
The function I want to debug is 'Respond'</p>

<pre><code>from __future__ import print_function

import re
import random
from nltk import compat

reflections = {
"i am"       : "you are",
"i was"      : "you were",
"i"          : "you",
"i'm"        : "you are",
"i'd"        : "you would",
"i've"       : "you have",
"i'll"       : "you will",
"my"         : "your",
"you are"    : "I am",
"you were"   : "I was",
"you've"     : "I have",
"you'll"     : "I will",
"your"       : "my",
"yours"      : "mine",
"you"        : "me",
"me"         : "you"
}

class Chat(object):
def __init__(self, pairs, reflections={}):
    self._pairs = [(re.compile(x, re.IGNORECASE),y) for (x,y) in pairs]
    self._reflections = reflections
    self._regex = self._compile_reflections()


def _compile_reflections(self):
    sorted_refl = sorted(self._reflections.keys(), key=len,
            reverse=True)
    return  re.compile(r"\b({0})\b".format("|".join(map(re.escape,
        sorted_refl))), re.IGNORECASE)

def _substitute(self, str):
   return self._regex.sub(lambda mo:
            self._reflections[mo.string[mo.start():mo.end()]],
                str.lower())

def _wildcards(self, response, match):
    pos = response.find('%')
    while pos &gt;= 0:
        num = int(response[pos+1:pos+2])
        response = response[:pos] + \
            self._substitute(match.group(num)) + \
            response[pos+2:]
        pos = response.find('%')
    return response

def respond(self, str):
    # check each pattern
    for (pattern, response) in self._pairs:
        match = pattern.match(str)

        # did the pattern match?
        if match:
            resp = random.choice(response)    # pick a random response
            resp = self._wildcards(resp, match) # process wildcards

            # fix munged punctuation at the end
            if resp[-2:] == '?.': resp = resp[:-2] + '.'
            if resp[-2:] == '??': resp = resp[:-2] + '?'
            return resp

# Hold a conversation with a chatbot
def converse(self, quit="quit"):
    input = ""
    while input != quit:
        input = quit
        try: input = compat.raw_input("&gt;")
        except EOFError:
            print(input)
        if input:
            while input[-1] in "!.": input = input[:-1]
            print(self.respond(input))
</code></pre>

<p>Any help will be very much appreciated. 
Thanks.</p>

<p>EDIT: 
I solved my problem but I haven't found a solution for the question. I'm using PyCharm (as suggested in the first comment) and it works like a charm. I can debug everything without any problem now. No file modification at all. I'm inclined to think that this is a bug in Python tools for Visual Studio. </p>

<p>Other members also got the similar issue, my suggestion is that you can use the PyCharm instead of PTVS as a workaround. Of course, you could also start a discussion(Q AND A) from this site for PTVS tool:</p>

<p><a href="https://visualstudiogallery.msdn.microsoft.com/9ea113de-a009-46cd-99f5-65ef0595f937" rel="nofollow">https://visualstudiogallery.msdn.microsoft.com/9ea113de-a009-46cd-99f5-65ef0595f937</a></p>

python python-3.x visual-studio-2015 visual-studio-debugging