#77 achieve 100% test coverage for indicators - stddev
#77 achieve 100% test coverage for indicators - tema
#77 achieve 100% test coverage for indicators - trima
#77 achieve 100% test coverage for indicators - truerange
#77 achieve 100% test coverage for indicators - tsf
#77 achieve 100% test coverage for indicators - typprice
#77 achieve 100% test coverage for indicators - var
#77 achieve 100% test coverage for indicators - willr
#77 achieve 100% test coverage for indicators - wma