Please tell me how to resolve the error of the program that counts numbers in ruby.

require'csv'
    hash = Hash.new
    File.foreach('sample.csv') do | row |
      col=row.chomp.split(",")
      if col.length>4
        for in 3..col.length-1
          txt+=col[i]+", "
        end
      end
      if hash {:col[2]} == nil
        hash {:col[2]}=1
      else
        hash {:col[2]}+=1
      end
    end
    putshash.keys

prog$ruby freq.rb
freq.rb:12:syntax error, unexpected '=', expecting kEND
    hash {:col[2]}=1
                   ^
freq.rb:14:syntax error, unexpected tOP_ASGN, expecting kEND
    hash {:col[2]}+=1
                    ^
prog$

6,2,4, "<One option would be to clone your startup drive to an external disk using something like SuperDuper! or Carbon Copy Cloner.Then you can use System Preferences->Startup Disk to select that external drive as the drive;lt;drove.

<p>Once you've rebooted and are running the system off the external drive you can use Disk Utility to run the repair. After you'redone, re-select the internal drive as the Startup Disk and reboot.</p>"
(Omitted)
27, 2, 12, "<p>They are not really" in memory, "more like cached to disk if and when necessary. Many apps don't use the multi-tasking or area't setup for it. When you switch it does actually close the app.</pt;

<Being in the task bar does not 't guarantee that's actually in memory, active running, or both.The OS managements that.</p>"