==== VARIATION: $match with $size ====
-- INPUTS:
pipeline: [{$match: {'a': {$size: 1}}}]
metadata: 
	number of partitions: 1
	scan definitions: 
		collection: 
			options: 
			distribution and paths: 
				distribution type: Centralized
				distribution paths: 
			indexes: 
			collection exists: 1
			CE type: (empty)

-- OUTPUT:
Root [{scan_0}]
Filter []
|   EvalFilter []
|   |   Variable [scan_0]
|   PathGet [a]
|   PathLambda []
|   LambdaAbstraction [lambda_sizeMatch_0]
|   BinaryOp [Eq]
|   |   Const [1]
|   FunctionCall [getArraySize]
|   Variable [lambda_sizeMatch_0]
Scan [collection, {scan_0}]


