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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 GetRowCache(self, query):
 """Retrieves the row cache for a specific query. The row cache is a set that contains hashes of values in a row. The row cache is used to find duplicate row when a database and a database with a WAL file is parsed. Args: query (str):
 query. Returns: set: hashes of the rows that have been parsed. """

    query_hash = hash(query)
    if query_hash not in self._row_caches:
      self._row_caches[query_hash] = set()
    return self._row_caches[query_hash]