title: Io Language: Exception: Sequence does not respond to 'openForReading'
body: <p>I'm study "seven languages in seven weeks".</p>
  
  <p>On Io charpter, I run following example failed with following exception.</p>
  
  <pre><code>#phonebook.io
  OperatorTable addAssignOperator(":", "atPutNumber")
  curlyBrackets := method(
    r := Map clone
    call message arguments foreach(arg,
         r doMessage(arg)
         )
    r
  )
  
  Map atPutNumber := method(
    self atPut(
         call evalArgAt(0) asMutable removePrefix("\"") removeSuffix("\""),
         call evalArgAt(1))
  )
  
  s := File with("phonebook.txt" openForReading contents)
  
  phoneNumbers := doString(s)
  phoneNumbers keys println
  phoneNumbers values println
  </code></pre>
  
  <h1>phonebook.txt</h1>
  
  <pre><code>{
          "Bob  Smith" : "12345",
          "Mary Walsh" : "5678"
  }
  </code></pre>
  
  <p>Exception message:</p>
  
  <blockquote>
    <p>Exception: Sequence does not respond to 'openForReading'   ---------<br>
    Sequence openForReading              phonebook.io 16   File with<br>
    phonebook.io 16   CLI doFile                           Z_CLI.io 140<br>
    CLI run                              IoState_runCLI() 1</p>
  </blockquote>
  
  <p>phonebook.io and phonebook.txt in same folder.</p>