cheat sheets.

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Ruby naming conventions:
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   local variables,
   arrays,
   hashes,
   method names
      begin with lower case letter

   global variables
      begin with $

   instance variables
      begin with @
      (@ represents 'attribute of an object')

   class variables
      begin with @@
      (@@ represents 'attribute for all related objects')

   constants,
   class names,
      begin with capital letter e.g.
      class Myclass
         def etc...

      create an instance:
      myinstance = Myclass.new("myparam")

   symbols
      begin with :
      :varname - pass in a symbol i.e. name of variable not value