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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 drop_index(self, index_or_name):
 """Drops the specified index on this collection. Can be used on non-existant collections or collections with no indexes. Raises OperationFailure on an error (e.g. trying to drop an index that does not exist). `index_or_name` can be either an index name (as returned by `create_index`), or an index specifier (as passed to `create_index`). An index specifier should be a list of (key, direction) pairs. Raises TypeError if index is not an instance of (str, unicode, list). .. warning:: if a custom name was used on index creation (by passing the `name` parameter to :meth:`create_index` or :meth:`ensure_index`) the index **must** be dropped by name. :Parameters: - `index_or_name`: index (or name of index) to drop .. note:: The :attr:`~pymongo.collection.Collection.write_concern` of this collection is automatically applied to this operation when using MongoDB >= 3.4. .. versionchanged:: 3.4 Apply this collection's write concern automatically to this operation when connected to MongoDB >= 3.4. """

        name = index_or_name
        if isinstance(index_or_name, list):
            name = helpers._gen_index_name(index_or_name)

        if not isinstance(name, string_type):
            raise TypeError("index_or_name must be an index name or list")

        self.__database.client._purge_index(
            self.__database.name, self.__name, name)
        cmd = SON([("dropIndexes", self.__name), ("index", name)])
        with self._socket_for_writes() as sock_info:
            self._command(sock_info,
                          cmd,
                          read_preference=ReadPreference.PRIMARY,
                          allowable_errors=["ns not found"],
                          write_concern=self.write_concern,
                          parse_write_concern_error=True)