def intersperse(enum, val)
      enum.inject([]) {|a, e| a << e << val}[0...-1]
    end
def intersperse(enum, val)
      enum.inject([]) {|a, e| a << e << val}[0...-1]
    end
Intersperses a value in an enumerable, as would be done with `Array#join`
 but without concatenating the array together afterwards.

 @param enum [Enumerable]
 @param val
 @return [Array]