store
store(path: Expr, val: Expr)
store writes val to the specified path assuming it is valid. Store does not evaluate to anything (in the future it may evaluate to the result of the store).
A new write will be initiated each time the value of either argument changes. For example, if the path changes to a new valid path, then the most recent val will be written immediatly to that new path.
e.g.
store("/tmp/thing", 42)
write 42 to /tmp/thing