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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 _compute_symbolic_link_mapping( directory: str, extensions: Iterable[str] ) -> Dict[str, str]: """ Given a shared analysis directory, produce a mapping from actual source files to files contained within this directory. Only includes files which have one of the provided extensions. Watchman watches actual source files, so when a change is detected to a file, this mapping can be used to identify what file changed from Pyre's perspective. """

    symbolic_links = {}
    try:
        for symbolic_link in find_paths_with_extensions(directory, extensions):
            symbolic_links[os.path.realpath(symbolic_link)] = symbolic_link
    except subprocess.CalledProcessError as error:
        LOG.warning(
            "Exception encountered trying to find source files "
            "in the analysis directory: `%s`",
            error,
        )
        LOG.warning("Starting with an empty set of tracked files.")
    return symbolic_links