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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 x_www_form_urlencoded(post_data):
 """ convert origin dict to x-www-form-urlencoded Args: post_data (dict):
 {"a": 1, "b":2} Returns: str: a=1&b=2 """

    if isinstance(post_data, dict):
        return "&".join([
            u"{}={}".format(key, value)
            for key, value in post_data.items()
        ])
    else:
        return post_data