# skeleton of a function that collects lifetables, exposures, death counts,
# and stacks all countries, years, sexes
# package can be pain to install, try different stuff, seek help
library(HMDHFDplus)
Countries <- getHMDcountries() # returns vector of HMD country codes

# us <- "HMD username" # change to yours: you need to be registered at www.mortality.org
# pw <- "HMD password" # change to yours
# makes long data frame of HMD lifetables, takes several minutes to run
LT <- do.call(rbind,  # (idiom to rbind a list of data.frames together)
         # lapply() is like looping, except it sticks everything in a lsit for you,
         # sometimes also a bit faster, and usually more elegant...
         lapply(Countries, function(XYZ, us, pw){ # here define an 'anonymous' function.
           # print progress to console
					 cat(XYZ,"\n")
           # male lifetables
                    LTM      <- readHMDweb(XYZ, "mltper_1x1", username = us, password = pw)
           # female lifetable
                    LTF      <- readHMDweb(XYZ, "fltper_1x1", username = us, password = pw)
           # add sex columns
                    LTM$Sex  <- "m"
                    LTF$Sex  <- "f"
           # ADD CODE HERE to add death count and exposure columns
           # after having read in those data objects

           # then stick together
                    LT       <- rbind(LTM, LTF)
           # add country name
                    LT$CNTRY <- XYZ
                    LT
                }, us = us, pw = pw))

# then the rest of the assignment basically follow from this object.
#