Sum function.

C# | Visual Basic | Visual C++ |
public static readonly ExprAggregate.ExprAggregate..::ExprAggregateOp SUM
Public Shared ReadOnly SUM As ExprAggregate..::ExprAggregateOp
public: static initonly ExprAggregate..::ExprAggregateOp^ SUM

Computes the sum of the subexpression
across all input values.