def duplicable?(obj)
      case obj
      when NilClass, FalseClass, TrueClass, Symbol, Numeric
        false
      else
        true
      end
    end
def duplicable?(obj)
      case obj
      when NilClass, FalseClass, TrueClass, Symbol, Numeric
        false
      else
        true
      end
    end
Internal: Check if object can safely be .dup'd.

 Similar to ActiveSupport #duplicable? check.

 obj - Any Object

 Returns false if .dup would raise a TypeError, otherwise true.