class interface DICTIONARY [ELEMENT] feature

   put (x: ELEMENT; key: STRING) is
   -- Insert x so that it will be retrievable through key.
    require
     count <= capacity
     not key.empty
    ensure
     has(x)
     item(key) = x
     count = old count + 1

   ... Interface specifications of other features ...

   invariant
    0 <= count
    count <= capacity

  end -- class interface DICTIONARY