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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def deduce_helpful_msg(req):
 # type: (str) -> str """Returns helpful msg in case requirements file does not exist, or cannot be parsed. :params req: Requirements file path """

    msg = ""
    if os.path.exists(req):
        msg = " It does exist."
        # Try to parse and check if it is a requirements file.
        try:
            with open(req, 'r') as fp:
                # parse first line only
                next(parse_requirements(fp.read()))
                msg += " The argument you provided " + \
                    "(%s) appears to be a" % (req) + \
                    " requirements file. If that is the" + \
                    " case, use the '-r' flag to install" + \
                    " the packages specified within it."
        except RequirementParseError:
            logger.debug("Cannot parse '%s' as requirements \
            file" % (req), exc_info=True)
    else:
        msg += " File '%s' does not exist." % (req)
    return msg