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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 get_source(self, path_or_url):
 """Returns the source image file descriptor. path_or_url: Path to the source image as an absolute path, a path relative to `self.base_path` or a URL beginning with `http[s]` """

        if path_or_url.startswith(('http://', 'https://')):
            try:
                return urlopen(path_or_url)
            except IOError:
                return None

        fullpath = path_or_url
        if not os.path.isabs(path_or_url):
            fullpath = os.path.join(self.base_path, path_or_url)
        try:
            return io.open(fullpath, 'rb')
        except IOError:
            return None