anchor.diff:  |java.math.BigDecimal
   |the statistical variance for the population for all non-null values
   
  -|agg(_expression_)
  -|any
  -|any
  -|customizes the aggregation logic in _expression_ and returns single value
  +//|agg(_expression_)
  +//|any
  +//|any
  +//|customizes the aggregation logic in _expression_ and returns single value
   
   |===
   
  
positive.code: include::../test/org/apache/groovy/ginq/GinqTest.groovy[tags=ginq_aggfunction_02,indent=0]
  ----
  
  [source, groovy]
  ----
  include::../test/org/apache/groovy/ginq/GinqTest.groovy[tags=ginq_aggfunction_01,indent=0]
  ----
  
  [source, groovy]
  ----
  
negative.code: include::../test/org/apache/groovy/ginq/GinqTest.groovy[tags=ginq_grouping_12,indent=0]
  ----
  
  ////
  [source, sql]
  ----
  include::../test/org/apache/groovy/ginq/GinqTest.groovy[tags=ginq_grouping_03,indent=0]
  