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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 read(self, input_file):
 """ Reads an InputHeader from `input_file`. The input header is read as a sequence of *<key>***:***<value>* pairs separated by a newline. The end of the input header is signalled by an empty line or an end-of-file. :param input_file: File-like object that supports iteration over lines """

        key, value = None, None
        import sys
        for line in input_file:
            if line == '\n':
                break
            if line[-1:] == '\n':
                line = line[:-1]
            item = line.split(':', 1)
            if len(item) == 2:
                # start of a new item
                self._update(key, value)
                key, value = item[0], urllib.unquote(item[1])
            elif key is not None:
                # continuation of the current item
                value = '\n'.join([value, urllib.unquote(line)])

        self._update(key, value)
        return