Merge function
mrg (expr1, expr2, …, exprN)
parameters
expr1, expr2, …, exprN:
symbols or stream of data to be merged into a single data stream.
variable number of parameters.
examples
mrg(
wagg("/GCL[0]", startday:mon, endday:wed),
wagg("/GCL[0]", startday:thu, endday:fri, reportday:fri)
)