def include?(key)
      if @my_vars.include?(key)
        true
      else
        @coa_vars.find do |coa_vars|
          coa_vars.include?(key)
        end
      end
    end
def include?(key)
      if @my_vars.include?(key)
        true
      else
        @coa_vars.find do |coa_vars|
          coa_vars.include?(key)
        end
      end
    end
Check if the VarSet contains a variable.

 @param key [String, Symbol] The variable name.

 @return [Boolean] Whether the VarSet contains the variable.