Add more example code standards (#1126)
Add more example code standards (#1126)

Co-authored-by: Meghan Jones <b6fecba088d0ca1791bd419c72e553d62e7cbe73@alum.mit.edu>
Co-authored-by: Dongdong Tian <3eae6d0b95aef6af8a0d785fe9f127268703c43c@gmail.com>
GenericMappingTools/gmt-python,GenericMappingTools/gmt-python