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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 matrix_undirected_unweighted(user):
 """ Returns an undirected, unweighted matrix where an edge exists if the relationship is reciprocated. """

    matrix = matrix_undirected_weighted(user, interaction=None)
    for a, b in combinations(range(len(matrix)), 2):
        if matrix[a][b] is None or matrix[b][a] is None:
            continue

        if matrix[a][b] > 0 and matrix[b][a] > 0:
            matrix[a][b], matrix[b][a] = 1, 1

    return matrix