diff --git a/Slides/snippet_helper.py b/Slides/snippet_helper.py
index 0d1df8d..b6680b8 100644
--- a/Slides/snippet_helper.py
+++ b/Slides/snippet_helper.py
@@ -1,491 +1,491 @@
 #!/usr/bin/env python3
 
 import subprocess
 import os
 import re
 import abc
 from pygments import highlight
 from pygments.lexers import CppLexer
 from pygments.lexers import PythonLexer
 from pygments.lexers import MatlabLexer
 from pygments.formatters import HtmlFormatter
 from pygments.formatters import LatexFormatter
 from pygments import token
 from IPython.display import HTML
 from tempfile import NamedTemporaryFile
 ################################################################
 
 
 class SlicedSnippet(object):
     """
     When you slice a snippet, this object is returned
     so that all your operations can apply directly to the snippet if need be.
     """
 
     def __init__(self, snippet, slice):
         self.start = slice.start
         if slice.start is None:
             self.start = 1
         self.end = slice.stop-1
         self.snippet = snippet
 
     def pigment(self, **kwargs):
         kwargs['start'] = self.start
         kwargs['end'] = self.end
         return self.snippet.pigment(**kwargs)
 
 
 class Snippet(abc.ABC):
     """
     Snippet objects manipulate codes.
     """
 
     default_output = 'html'
     default_line_numbering = False
 
     def __getitem__(self, slice):
         return SlicedSnippet(self, slice)
 
     def __init__(self, inp, format_flag=False,
                  compile_flag=False,
                  working_dir='/tmp'):
 
         self.working_dir = working_dir
 
         try:
             self.loadfile(inp)
         except Exception:
             self.content = inp.strip()
 
         if format_flag:
             self.format()
         if compile_flag:
             self.compile()
 
         # elif language == 'matlab':
         #     self.lexer = MatlabLexer()
 
     def save(self, filename):
         """
         Saves the snippet in another file
 
         :param filename: The filename to save the snippet to
         """
 
         f = open(filename, 'w')
         f.write(self.content)
         f.close()
 
     def loadfile(self, inp):
         filename = inp
         full_filename = os.path.realpath(filename)
         f = open(full_filename)
         self.content = f.read()
         f.close()
 
     def getTemporaryFile(self, **kwargs):
         f = NamedTemporaryFile(dir=self.working_dir, **kwargs)
         f.write(self.content.encode())
         f.flush()
         return f
 
     @abc.abstractmethod
     def format(self):
         raise RuntimeError('pure virtual routine')
 
     @abc.abstractmethod
     def execute(self, working_dir='/tmp', args='', libraries=''):
         raise RuntimeError('pure virtual routine')
 
     def compile(self, working_dir='/tmp'):
         raise RuntimeError('pure virtual routine')
 
     def get_lines(self):
         return self.content.split('\n')
 
     def get_content(self):
         return self.content
 
     def __str__(self):
         _content = self.content.split('\n')
         ret = ""
         for i, line in enumerate(_content):
             ret += '{0}: {1}\n'.format(i, line)
         return ret
 
     class KeywordLexer(object):
 
         def __init__(self, keyword):
             if keyword == 'curly_brackets':
                 keyword = '{|}'
             self.keyword = keyword
 
         def get_tokens(self, text):
             pattern = '(' + self.keyword + ')'
             splits = re.split(pattern, text)
             if len(splits) == 1:
                 return [(token.Text, text)]
             res = []
             # print(splits)
             # print(token.Keyword.Type)
             for count, s in enumerate(splits):
                 # print(count, s)
                 if count % 2 == 0:
                     res.append((token.Text, s))
                 else:
                     res.append((token.Keyword.Type, s))
 
             # print(res)
             return res
 
     class LineLexer(object):
 
         def __init__(self, line_number):
             self.line_number = line_number
 
         def get_tokens(self, text):
             splits = text.split('\n')
             res = []
             splits1 = '\n'.join(splits[:self.line_number]) + '\n'
             splits2 = splits[self.line_number] + '\n'
             splits3 = '\n' + '\n'.join(splits[self.line_number + 1:]) + '\n'
             splits = [splits1] + [splits2] + [splits3]
             # print(splits)
             for count, s in enumerate(splits):
                 if count == 1:
                     res.append((token.Keyword.Type, s))
                 else:
                     res.append((token.Text, s))
 
             # print(res)
             return res
 
     class CustomLatexFormatter(LatexFormatter):
 
         def __init__(self, **kwargs):
             LatexFormatter.__init__(self, **kwargs)
 
         def format(self, tokens, outfile):
             res = []
             for t, s in tokens:
                 if t == token.Keyword.Type:
                     import pygments.formatters.latex as la
                     s = la.escape_tex(s, self.commandprefix)
                     s = r'\color{red}{\huge{' + s + '}}'
                     t = token.Escape
                 res.append((t, s))
             LatexFormatter.format(self, res, outfile)
 
     class CustomHtmlFormatter(HtmlFormatter):
 
         def __init__(self, **kwargs):
             HtmlFormatter.__init__(self, **kwargs)
 
         def format(self, tokens, outfile_final):
             # HtmlFormatter.format(self, tokens, outfile_final)
             # return
             from io import StringIO
             outfile = StringIO()
             res = []
             ss = []
             for t, s in tokens:
                 if t == token.Keyword.Type:
                     ss.append(s)
                     s = 'A' * 24
                     t = token.Text
                 res.append((t, s))
             # print(res)
             HtmlFormatter.format(self, res, outfile)
             final = outfile.getvalue()
             while ss:
                 s = ss.pop(0)
                 final = final.replace(
                     'A' * 24,
                     '<span style="color:red;font-size:150%">{0}</span>'.format(
                         s),
                     1)
             outfile_final.write(final)
 
     def pigment(self,
                 keyword=None, line_highlight=None,
                 start=None, end=None,
                 output=None, line_numbering=None):
 
         _content = self.content.split('\n')
         _content = [(c + '\n') for c in _content]
 
         if start is None:
             start = 1
         if end is None:
             end = len(_content)
 
         if output is None:
             output = self.default_output
 
         lexer = self.lexer
         if keyword is not None:
             lexer = self.KeywordLexer(keyword)
         elif line_highlight is not None:
             if line_highlight < start or line_highlight > end:
                 raise RuntimeError('line_highlight out of the sub snippet')
             line_highlight -= start
             lexer = self.LineLexer(line_highlight)
 
         if line_numbering is None:
             line_numbering = self.default_line_numbering
 
         if output == 'html':
             formatter = HtmlFormatter(
                 full=False, linenos=line_numbering, linenostart=start)
         elif output == 'latex':
             formatter = LatexFormatter(
                 full=False, linenos=line_numbering, linenostart=start)
 
         if (keyword is not None) or (line_highlight is not None):
             format_class = self.CustomHtmlFormatter
             if output == 'latex':
                 format_class = self.CustomLatexFormatter
             formatter = format_class(
                 full=False, linenos=line_numbering,
                 linenostart=start)
 
         snip = _content[start - 1:end]
         snip = ''.join(snip)
 
         colored_snippet = highlight(snip, lexer, formatter)
         # print(colored_snippet)
         if output == 'html':
             HTML_TEMPLATE = """<style>
             {}
             </style>
             {}
             """
             css = formatter.get_style_defs()
             colored_snippet = HTML(HTML_TEMPLATE.format(css, colored_snippet))
         return colored_snippet
 
     @staticmethod
     def getLatexStyleDefs():
         return LatexFormatter(full=True).get_style_defs()
 
 ################################################################
 
 
 class CPPSnippet(Snippet):
     """
     Snippet objects manipulate Cpp codes.
     At construction it can be formatted using clang-format
     and it can be compiled to check for consistency.
     """
 
     class CompilationError(Exception):
         """ Compilation error """
         pass
 
     def __init__(self, inp, include_paths=None, **kwargs):
 
         if include_paths is None:
             self.include_paths = []
         else:
             self.include_paths = [
                 os.path.abspath(i) for i in include_paths]
 
         Snippet.__init__(self, inp, **kwargs)
 
         self.lexer = CppLexer()
 
     def format(self):
         f = self.getTemporaryFile()
         p = subprocess.Popen(
             'clang-format {0}'.format(f.name),
             shell=True, stdout=subprocess.PIPE)
         stdout, stderr = p.communicate()
         if p.returncode:
             raise RuntimeError('Failed to launch clang-format')
         formatted_file = stdout
         self.content = formatted_file.decode('utf-8')
 
     def execute(self, working_dir='/tmp', args='', libraries=''):
         self.compile(working_dir=working_dir)
         f = self.getTemporaryFile(suffix='.cpp', delete=False)
         working_dir = os.path.dirname(f.name)
         # file_dir = os.path.dirname(self.full_filename)
         previous_dir = os.getcwd()
         os.chdir(working_dir)
         include_paths = self.include_paths + [working_dir]
         include_paths = ['-I {0}'.format(a) for a in include_paths]
         include_paths = ' '.join(include_paths)
 
         p = subprocess.Popen(
             'g++ -Wall -Wextra {1} {2} -o exec {0}'.format(
                 f.name, include_paths, libraries),
             shell=True,
             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         stdout, stderr = p.communicate()
 
         ret = p.returncode
         if ret != 0:
             return ret, stdout, stderr
 
         p = subprocess.Popen(
             './exec {0}'.format(args), shell=True,
             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         stdout, stderr = p.communicate()
         ret = p.returncode
 
         os.chdir(previous_dir)
         return ret, stdout, stderr
 
     def compile(self):
         f = self.getTemporaryFile(suffix='.cpp', delete=False)
 
         working_dir = os.path.dirname(f.name)
         # file_dir = os.path.dirname(self.full_filename)
         previous_dir = os.getcwd()
         os.chdir(self.working_dir)
         include_paths = self.include_paths + [working_dir]
         include_paths = ['-I {0}'.format(a) for a in include_paths]
         include_paths = ' '.join(include_paths)
         cmd = 'g++ -Wall -Wextra {1} -c {0}'.format(f.name, include_paths)
         p = subprocess.Popen(cmd, shell=True, stderr=subprocess.PIPE)
         stdout, stderr = p.communicate()
         ret = p.returncode
         os.chdir(previous_dir)
         if ret != 0:
             raise CPPSnippet.CompilationError('compilation failed\n' +
                                               cmd + '\n' +
                                               stderr.decode('utf-8'))
 
         os.remove(f.name)
         o_file = os.path.splitext(f.name)[0] + '.o'
         os.remove(o_file)
 
 ################################################################
 
 
 class PythonSnippet(Snippet):
     """
     Snippet objects manipulate Python codes.
     At construction it can be formatted using autopep8.
     """
 
     def __init__(self, inp, **kwargs):
 
         Snippet.__init__(self, inp, **kwargs)
 
         self.lexer = PythonLexer()
 
     def format(self):
         f = self.getTemporaryFile()
         p = subprocess.Popen(
             'autopep8 {0}'.format(f.name),
             shell=True, stdout=subprocess.PIPE)
         stdout, stderr = p.communicate()
         if p.returncode:
             raise RuntimeError('Failed to launch autopep8')
         formatted_file = stdout
         self.content = formatted_file.decode('utf-8')
 
     def execute(self, args=[]):
-        f = self.getTemporaryFile(delete=False, suffix='.py')
+        f = self.getTemporaryFile(suffix='.py')
         cmd = 'python3 {0} {1}'.format(f.name, ' '.join(args))
         previous_dir = os.getcwd()
         os.chdir(self.working_dir)
 
         p = subprocess.Popen(
-            cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            cmd, shell=True, stdout=subprocess.PIPE)
         stdout, stderr = p.communicate()
         os.chdir(previous_dir)
         if p.returncode:
             raise RuntimeError('Failed to run snippet\n' +
                                cmd + '\n' + stderr.decode())
         return stdout
 
 
 ################################################################
 
 
 class SnippetCollection(Snippet):
 
     def __init__(self):
         self.functions = dict()
         self.func_names = []
 
     def addFunction(self, f_name, code):
         if f_name in self.functions:
             raise RuntimeError('function already declared')
         self.func_names.append(f_name)
         self.functions[f_name] = Snippet(code, format_flag=True)
         self.compile()
 
     def __getitem__(self, key):
         return self.functions[key]
 
     def flatten(self):
         global_input = """
 #include <iostream>
 #include <cmath>
 #include <cstdlib>
 #include <cassert>
 
 """ + '/' * 70 + '\n\n'
 
         for f_name in self.func_names:
             global_input += "void {0}(){{\n".format(f_name)
             global_input += self.functions[f_name].content
             global_input += '\n}\n\n' + '/' * 70 + '\n\n'
 
         global_input += """
 int main(int argc, char ** argv){\n"""
         for f_name in self.func_names:
             global_input += f_name + '();\n'
         global_input += '\n}\n'
 
         flat = Snippet(global_input,
                        format_flag=True)
         return flat
 
     def compile(self, **kwargs):
         global_snippet = self.flatten()
         global_snippet.compile(**kwargs)
 
     def save(self, filename):
         global_snippet = self.flatten()
         open(filename, 'w').write(global_snippet.content)
 
     def pigment(self, *args):
         return self.flatten().pigment(*args)
 
     def last(self):
         return self.functions[self.func_names[-1]]
 
 ################################################################
 
 # def printMatlab(code):
 #
 #     html_snippet = highlight(
 #         code, MatlabLexer(),
 #         HtmlFormatter(full=True, style='colorful',
 #                       classprefix='matlab_'))
 #
 #     display(HTML(html_snippet))
 #     # return html_snippet
 
 
 # ## testing
 
 # Snippet.default_output = 'latex'
 # Snippet.default_line_numbering = True
 #
 # snippet = SnippetCollection()
 #  snippet.addFunction('if_syntax', '''
 #   int p, q;
 #   if (p > q) {
 #     /*
 #     Statement1;
 #     Statement2;
 #     */
 #   }
 # ''')
 #
 # print (snippet['if_syntax'].pigment())