Faker.DateTime.forward(4)
#=> %DateTime{calendar: Calendar.ISO, day: 25, hour: 6,
#=> microsecond: {922180, 6}, minute: 2, month: 12, second: 17,
#=> std_offset: 0, time_zone: "Etc/UTC", utc_offset: 0, year: 2016,
#=> zone_abbr: "UTC"}
Faker.DateTime.backward(4)
#=> %DateTime{calendar: Calendar.ISO, day: 20, hour: 6,
#=> microsecond: {922180, 6}, minute: 2, month: 12, second: 17,
#=> std_offset: 0, time_zone: "Etc/UTC", utc_offset: 0, year: 2016,
#=> zone_abbr: "UTC"}
Faker.DateTime.between(~N[2016-12-20 00:00:00], ~N[2016-12-25 00:00:00])
#=> %DateTime{calendar: Calendar.ISO, day: 22, hour: 7,
#=> microsecond: {753572, 6}, minute: 56, month: 12, second: 26,
#=> std_offset: 0, time_zone: "Etc/UTC", utc_offset: 0, year: 2016,
#=> zone_abbr: "UTC"}