def get_adjacency_cells(cur):
    """
    Returns list of cells in the adjacency data

    Parameters:
    -----------
    cur : MySQLdb cursor

    """
    sql = ("select distinct(pre) from adjacency2 "
           "union "
           "select distinct(post) from adjacency2")
    cur.execute(sql)
    return [a[0] for a in cur.fetchall()]