Function that checks that a given object is a PipeOp and throws an error if not.
PipeOp
assert_pipeop(x)
(any) Object to check.
any
PipeOp invisible(x)
invisible(x)
Other Graph operators: %>>%, as_graph, as_pipeop, assert_graph, greplicate, gunion
%>>%
as_graph
as_pipeop
assert_graph
greplicate
gunion