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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 replace_uri(rdf, fromuri, touri):
 """Replace all occurrences of fromuri with touri in the given model. If touri is a list or tuple of URIRef, all values will be inserted. If touri=None, will delete all occurrences of fromuri instead. """

    replace_subject(rdf, fromuri, touri)
    replace_predicate(rdf, fromuri, touri)
    replace_object(rdf, fromuri, touri)