Get the continent that a particular country belongs to
Examples
# view the searchable countries, return first 15
names(continentOf)[1:15]
#> [1] "afghanistan" "albania" "algeria"
#> [4] "andorra" "angola" "antigua and barbuda"
#> [7] "argentina" "anguilla" "armenia"
#> [10] "austria" "australia" "azerbaijan"
#> [13] "bahrain" "bahamas" "bangladesh"
#task 1: view the continent of algeria
continentOf$algeria
#> [1] "Africa"
#task 2: view the continent of nigeria
continentOf$nigeria
#> [1] "Africa"
#task 3: view the continent of multiple countries
continentOf[c("niger","china","colombia")]
#> $niger
#> [1] "Africa"
#>
#> $china
#> [1] "Asia"
#>
#> $colombia
#> [1] "South America"
#>
#task 4: if the continent is not available
continentOf[c("niger","china","randomtest")]
#> $niger
#> [1] "Africa"
#>
#> $china
#> [1] "Asia"
#>
#> $<NA>
#> NULL
#>