title: Calculation with an action button and using in another ObserveEvent
body: <p>Let's say I have two action buttons. When I press "Go!", I want to calculate a value and then, by the pressing the second action button, I want to use the calculated value in another calculation. This code does not work and gives an error like this:</p>
  
  <p>"Warning: Error in observeEventHandler: object 'coeff' not found"</p>
  
  <p>Why it does not give me an answer?</p>
  
  <pre><code>library(shiny)
  
  ui &lt;- fluidPage(
    actionButton(inputId = "AB", label = "Go!"),
    actionButton(inputId = "AB1", label = "Calculate!")
  )
  
  server &lt;- function(input, output, session) {
    observeEvent(input$AB,{
      coeff &lt;- sum(1:15)
    })
  
    observeEvent(input$AB1,{
      calculatedValue &lt;- coeff*10
    })
  
  }
  
  shinyApp(ui = ui, server = server)
  </code></pre>