code: def namedb_get_preorder(cur, preorder_hash, current_block_number, include_expired=False, expiry_time=None):
      
  
      select_query = None 
      args = None 
  
      if include_expired:
          select_query = "SELECT * FROM preorders WHERE preorder_hash = ?;"
          args = (preorder_hash,)
  
      else:
          assert expiry_time is not None, "expiry_time is required with include_expired"
          select_query = "SELECT * FROM preorders WHERE preorder_hash = ? AND block_number < ?;"
          args = (preorder_hash, expiry_time + current_block_number)
  
      preorder_rows = namedb_query_execute( cur, select_query, (preorder_hash,))
      preorder_row = preorder_rows.fetchone()
      if preorder_row is None:
          # no such preorder 
          return None
  
      preorder_rec = {}
      preorder_rec.update( preorder_row )
      
      return preorder_rec
docs: Get a preorder record by hash.
      If include_expired is set, then so must expiry_time
      Return None if not found.