# File lib/fog/aws/efs.rb, line 95
        def setup_credentials(options)
          @aws_access_key_id         = options[:aws_access_key_id]
          @aws_secret_access_key     = options[:aws_secret_access_key]
          @aws_session_token         = options[:aws_session_token]
          @aws_credentials_expire_at = options[:aws_credentials_expire_at]

          #global services that have no region are signed with the us-east-1 region
          #the only exception is GovCloud, which requires the region to be explicitly specified as us-gov-west-1
          @signer = Fog::AWS::SignatureV4.new(@aws_access_key_id, @aws_secret_access_key, @region, 'elasticfilesystem')
        end