Note 8 - Stock Warrants (Details) - Schedule of Stockholders' Equity Note, Warrants or Rights - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Stockholders' Equity Note, Warrants or Rights [Abstract]
Warrants, Outstanding	1,167,653		142,653
Warrants, Outstanding Weighted-Average Exercise Price	$ 0.10	$ 2.18	$ 17.42
Warrants, Outstanding Weighted-Average Remaining Contractual Terms	4 years 6 months	4 years 131 days	1 year
Warrants, Exercisable	1,425,000
Warrants, Exercisable Weighted-Average Exercise Price	$ 0.10
Warrants, Exercisable Weighted-Average Remaining Contractual Terms	4 years 6 months
Warrants, Granted	400,000	1,025,000
Warrants, Granted Weighted-Average Exercise Price	$ 0.10	$ 0.10
Warrants, Granted, Weighted-Average Remaining Contractual Terms	4 years 6 months	4 years 339 days
Warrants, Expired	(142,653)	0
Warrants, Expired Weighted-Average Exercise Price	$ 17.42	$ 0
Warrants, Outstanding	1,425,000	1,167,653