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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 namedb_get_num_block_vtxs( cur, block_number ):
 """ How many virtual transactions were processed for this block? """
 
    select_query = "SELECT vtxindex FROM history WHERE history_id = ?;"
    args = (block_number,)

    rows = namedb_query_execute( cur, select_query, args )
    count = 0
    for r in rows:
        count += 1

    return count