Array node

[trisyoungs]

Describe the feature / issue
A useful addition to the ProcedureNode ecosystem would be an ArrayNode (perhaps in 1D, 2D, and 3D flavours) with the simple purpose to iterate over a range of values, set as ExpressionVariables, and which can be then be used by other nodes. For example, creating a 2D array of molecules at specific, regular coordinates.