def suck_out_formats(reporters):
    """Builds a dictionary mapping edition keys to their cite_format if any.

    The dictionary takes the form of:
        {
            'T.C. Summary Opinion': '{reporter} {volume}-{page}',
            'T.C. Memo.': '{reporter} {volume}-{page}'
            ...
        }

    In other words, this lets you go from an edition match to its parent key.
    """
    formats_out = {}
    for reporter_key, data_list in reporters.items():
        # For each reporter key...
        for data in data_list:
            # Map the cite_format if it exists
            for edition_key, edition_value in data["editions"].items():
                try:
                    formats_out[edition_key] = data["cite_format"]
                except KeyError:
                    # The item wasn't there; add it.
                    pass
    return formats_out