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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 apply_upstring(upstring, component_list):
 """Update the dictionaries resulting from ``parse_array_start`` with the "up" key based on the upstring returned from ``parse_upstring``. The function assumes that the upstring and component_list parameters passed in are from the same device array stanza of a ``/proc/mdstat`` file. The function modifies component_list in place, adding or updating the value of the "up" key to True if there is a corresponding ``U`` in the upstring string, or to False if there is a corresponding ``_``. If there the number of rows in component_list does not match the number of characters in upstring, an ``AssertionError`` is raised. Parameters upstring : str String sequence of ``U``s and ``_``s as determined by the ``parse_upstring`` method component_list : list List of dictionaries output from the ``parse_array_start`` method. """

    assert len(upstring) == len(component_list)

    def add_up_key(comp_dict, up_indicator):
        assert up_indicator == 'U' or up_indicator == "_"
        comp_dict['up'] = up_indicator == 'U'

    for comp_dict, up_indicator in zip(component_list, upstring):
        add_up_key(comp_dict, up_indicator)