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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 _remove_from_ptr_size(self, ptr):
        # type: (path_table_record.PathTableRecord) -> int
        '''
        An internal method to remove a PTR from a VD, removing space from the VD if
        necessary.

        Parameters:
         ptr - The PTR to remove from the VD.
        Returns:
         The number of bytes to remove from the VDs (this may be zero).
        '''
        num_bytes_to_remove = 0
        for pvd in self.pvds:
            # The remove_from_ptr_size() returns True if the PVD no longer
            # needs the extra extents in the PTR that stored this directory.
            # We always remove 4 additional extents for that.
            if pvd.remove_from_ptr_size(path_table_record.PathTableRecord.record_length(ptr.len_di)):
                num_bytes_to_remove += 4 * self.pvd.logical_block_size()

        return num_bytes_to_remove