code: public int getIndexOfTve(TupleValueExpression tve) {
          SchemaColumn column = new SchemaColumn(
                  tve.getTableName(), tve.getTableAlias(),
                  tve.getColumnName(), tve.getColumnAlias(),
                  tve, tve.getDifferentiator());
          return findIndexOfColumn(column);
      }
docs: Convenience method for looking up the column offset for a TVE using
  getIndexOf().  This is a common operation because every TVE in every
  AbstractExpression in a plan node needs to have its column_idx updated
  during the column index resolution phase.