def update_self(parsed_response)
      instance_variables.each do |iv|
        instance_variable_set(iv, parsed_response[iv.to_s[1..-1].to_sym])
      end
      self
    end
def update_self(parsed_response)
      instance_variables.each do |iv|
        instance_variable_set(iv, parsed_response[iv.to_s[1..-1].to_sym])
      end
      self
    end
Private: Update the Pot instance variables

 parsed_response - a hash whose keys exactly match the instance variables for Monzo::Pot.

 Returns self (an instance of Monzo::Pot)