export(qme,qme.fit,lt,lt.fit,stls,stls.fit)
exportMethods(
    "coef",
    "fitted",
    "print",
    "residuals",
    "summary",
    "vcov" 
)
exportClasses(
    "lt",
     "qme",
     "stls",
     "summary.lt",
     "summary.qme",
     "summary.stls" 
)
import(stats,methods,truncreg)
importFrom(boot,boot)