local Observable = require "rx.observable"
local util = require "rx.util"

--- Returns a new Observable that transform the items emitted by an Observable into Observables,
-- then flatten the emissions from those into a single Observable
-- @arg {function} callback - The function to transform values from the original Observable.
-- @returns {Observable}
function Observable:flatMap(callback)
    callback = callback or util.identity
    return self:map(callback):flatten()
end