human
Complete the below
@jinja_filter('which')
def which(exe=None):

    ''''Python clone of /usr/bin/which'
    '''
assistant
#Here is the Python program you requested.
    def _is_executable_file_or_link(exe):
        return (os.access(exe, os.X_OK) and (os.path.isfile(exe) or os.path.islink(exe)))
    if exe:
        if _is_executable_file_or_link(exe):
            return exe
        ext_list = os.environ.get('PATHEXT', '.EXE').split(';')
        @real_memoize
        def _exe_has_ext():
            '\n                                                Do    a    case    insensitive    test    if    exe    has    a    file    extension    match    in\n                                                PATHEXT\n                                                '
            for ext in ext_list:
                try:
                    pattern = (('.*\\.' + ext.lstrip('.')) + '$')
                    re.match(pattern, exe, re.I).groups()
                    return True
                except AttributeError:
                    continue
            return False
        search_path = ((os.environ.get('PATH') and os.environ['PATH'].split(os.pathsep)) or list())
        for default_path in ['/bin', '/sbin', '/usr/bin', '/usr/sbin', '/usr/local/bin']:
            if (default_path not in search_path):
                search_path.append(default_path)
        os.environ['PATH'] = os.pathsep.join(search_path)
        for path in search_path:
            full_path = os.path.join(path, exe)
            if _is_executable_file_or_link(full_path):
                return full_path
            elif (salt.utils.platform.is_windows() and (not _exe_has_ext())):
                for ext in ext_list:
                    if _is_executable_file_or_link((full_path + ext)):
                        return (full_path + ext)
        log.trace("'{0}'    could    not    be    found    in    the    following    search    path:    '{1}'".format(exe, search_path))
    else:
        log.error('No    executable    was    passed    to    be    searched    by    salt.utils.path.which()')
    return None