def METHOD_NAME(self, string):
    """" Get the index of the string in the Shared String table. """
    if string not in self.string_table:
        # String isn't already stored in the table so add it.
        index = self.unique_count
        self.string_table[string] = index
        self.count += 1
        self.unique_count += 1
        return index
    else:
        # String exists in the table.
        index = self.string_table[string]
        self.count += 1
        return index