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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 to_sif_path(graph: BELGraph, path: str, sep: Optional[str] = None) -> None: """Write the graph as a tab-separated SIF file. to a file at the given path."""

    with open(path, 'w') as file:
        to_sif(graph, file, sep=sep)